It must be a hardware-specific issue of some kind. Here I have 4 USB devices connected full time, and no apparent problem with the new kernel:
root@imerabox:/var/log# cat kern.log | grep usb
Mar 20 08:43:39 imerabox kernel: [ 0.677915] usbcore: registered new interface driver usbfs
Mar 20 08:43:39 imerabox kernel: [ 0.679288] usbcore: registered new interface driver hub
Mar 20 08:43:39 imerabox kernel: [ 0.679883] usbcore: registered new device driver usb
Mar 20 08:43:39 imerabox kernel: [ 0.680925] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002
Mar 20 08:43:39 imerabox kernel: [ 0.680927] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
Mar 20 08:43:39 imerabox kernel: [ 0.680930] usb usb1: Product: xHCI Host Controller
Mar 20 08:43:39 imerabox kernel: [ 0.680932] usb usb1: Manufacturer: Linux 3.3-0.towo.1-siduction-amd64 xhci_hcd
Mar 20 08:43:39 imerabox kernel: [ 0.680935] usb usb1: SerialNumber: 0000:02:00.0
Mar 20 08:43:39 imerabox kernel: [ 0.684039] usb usb2: New USB device found, idVendor=1d6b, idProduct=0003
Mar 20 08:43:39 imerabox kernel: [ 0.684043] usb usb2: New USB device strings: Mfr=3, Product=2, SerialNumber=1
Mar 20 08:43:39 imerabox kernel: [ 0.684045] usb usb2: Product: xHCI Host Controller
Mar 20 08:43:39 imerabox kernel: [ 0.684047] usb usb2: Manufacturer: Linux 3.3-0.towo.1-siduction-amd64 xhci_hcd
Mar 20 08:43:39 imerabox kernel: [ 0.684050] usb usb2: SerialNumber: 0000:02:00.0
Mar 20 08:43:39 imerabox kernel: [ 0.697321] usb usb3: New USB device found, idVendor=1d6b, idProduct=0002
Mar 20 08:43:39 imerabox kernel: [ 0.697323] usb usb3: New USB device strings: Mfr=3, Product=2, SerialNumber=1
Mar 20 08:43:39 imerabox kernel: [ 0.697325] usb usb3: Product: EHCI Host Controller
Mar 20 08:43:39 imerabox kernel: [ 0.697327] usb usb3: Manufacturer: Linux 3.3-0.towo.1-siduction-amd64 ehci_hcd
Mar 20 08:43:39 imerabox kernel: [ 0.697328] usb usb3: SerialNumber: 0000:00:1a.7
Mar 20 08:43:39 imerabox kernel: [ 0.707309] usb usb4: New USB device found, idVendor=1d6b, idProduct=0002
Mar 20 08:43:39 imerabox kernel: [ 0.707311] usb usb4: New USB device strings: Mfr=3, Product=2, SerialNumber=1
Mar 20 08:43:39 imerabox kernel: [ 0.707312] usb usb4: Product: EHCI Host Controller
Mar 20 08:43:39 imerabox kernel: [ 0.707313] usb usb4: Manufacturer: Linux 3.3-0.towo.1-siduction-amd64 ehci_hcd
Mar 20 08:43:39 imerabox kernel: [ 0.707315] usb usb4: SerialNumber: 0000:00:1d.7
Mar 20 08:43:39 imerabox kernel: [ 0.707529] usb usb5: New USB device found, idVendor=1d6b, idProduct=0001
Mar 20 08:43:39 imerabox kernel: [ 0.707530] usb usb5: New USB device strings: Mfr=3, Product=2, SerialNumber=1
Mar 20 08:43:39 imerabox kernel: [ 0.707532] usb usb5: Product: UHCI Host Controller
Mar 20 08:43:39 imerabox kernel: [ 0.707533] usb usb5: Manufacturer: Linux 3.3-0.towo.1-siduction-amd64 uhci_hcd
Mar 20 08:43:39 imerabox kernel: [ 0.707534] usb usb5: SerialNumber: 0000:00:1a.0
Mar 20 08:43:39 imerabox kernel: [ 0.707731] usb usb6: New USB device found, idVendor=1d6b, idProduct=0001
Mar 20 08:43:39 imerabox kernel: [ 0.707733] usb usb6: New USB device strings: Mfr=3, Product=2, SerialNumber=1
Mar 20 08:43:39 imerabox kernel: [ 0.707734] usb usb6: Product: UHCI Host Controller
Mar 20 08:43:39 imerabox kernel: [ 0.707736] usb usb6: Manufacturer: Linux 3.3-0.towo.1-siduction-amd64 uhci_hcd
Mar 20 08:43:39 imerabox kernel: [ 0.707737] usb usb6: SerialNumber: 0000:00:1a.1
Mar 20 08:43:39 imerabox kernel: [ 0.707894] usb usb7: New USB device found, idVendor=1d6b, idProduct=0001
Mar 20 08:43:39 imerabox kernel: [ 0.707895] usb usb7: New USB device strings: Mfr=3, Product=2, SerialNumber=1
Mar 20 08:43:39 imerabox kernel: [ 0.707896] usb usb7: Product: UHCI Host Controller
Mar 20 08:43:39 imerabox kernel: [ 0.707898] usb usb7: Manufacturer: Linux 3.3-0.towo.1-siduction-amd64 uhci_hcd
Mar 20 08:43:39 imerabox kernel: [ 0.707899] usb usb7: SerialNumber: 0000:00:1a.2
Mar 20 08:43:39 imerabox kernel: [ 0.708083] usb usb8: New USB device found, idVendor=1d6b, idProduct=0001
Mar 20 08:43:39 imerabox kernel: [ 0.708085] usb usb8: New USB device strings: Mfr=3, Product=2, SerialNumber=1
Mar 20 08:43:39 imerabox kernel: [ 0.708086] usb usb8: Product: UHCI Host Controller
Mar 20 08:43:39 imerabox kernel: [ 0.708087] usb usb8: Manufacturer: Linux 3.3-0.towo.1-siduction-amd64 uhci_hcd
Mar 20 08:43:39 imerabox kernel: [ 0.708089] usb usb8: SerialNumber: 0000:00:1d.0
Mar 20 08:43:39 imerabox kernel: [ 0.708261] usb usb9: New USB device found, idVendor=1d6b, idProduct=0001
Mar 20 08:43:39 imerabox kernel: [ 0.708263] usb usb9: New USB device strings: Mfr=3, Product=2, SerialNumber=1
Mar 20 08:43:39 imerabox kernel: [ 0.708264] usb usb9: Product: UHCI Host Controller
Mar 20 08:43:39 imerabox kernel: [ 0.708266] usb usb9: Manufacturer: Linux 3.3-0.towo.1-siduction-amd64 uhci_hcd
Mar 20 08:43:39 imerabox kernel: [ 0.708267] usb usb9: SerialNumber: 0000:00:1d.1
Mar 20 08:43:39 imerabox kernel: [ 0.708451] usb usb10: New USB device found, idVendor=1d6b, idProduct=0001
Mar 20 08:43:39 imerabox kernel: [ 0.708453] usb usb10: New USB device strings: Mfr=3, Product=2, SerialNumber=1
Mar 20 08:43:39 imerabox kernel: [ 0.708454] usb usb10: Product: UHCI Host Controller
Mar 20 08:43:39 imerabox kernel: [ 0.708455] usb usb10: Manufacturer: Linux 3.3-0.towo.1-siduction-amd64 uhci_hcd
Mar 20 08:43:39 imerabox kernel: [ 0.708457] usb usb10: SerialNumber: 0000:00:1d.2
Mar 20 08:43:39 imerabox kernel: [ 1.099946] usb 3-3: new high-speed USB device number 3 using ehci_hcd
Mar 20 08:43:39 imerabox kernel: [ 1.215475] usb 3-3: New USB device found, idVendor=04a9, idProduct=10a8
Mar 20 08:43:39 imerabox kernel: [ 1.215476] usb 3-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
Mar 20 08:43:39 imerabox kernel: [ 1.215478] usb 3-3: Product: iP6220D
Mar 20 08:43:39 imerabox kernel: [ 1.215479] usb 3-3: Manufacturer: Canon
Mar 20 08:43:39 imerabox kernel: [ 1.215480] usb 3-3: SerialNumber: A0287B
Mar 20 08:43:39 imerabox kernel: [ 1.217236] usbcore: registered new interface driver uas
Mar 20 08:43:39 imerabox kernel: [ 1.420849] usb 5-1: new full-speed USB device number 2 using uhci_hcd
Mar 20 08:43:39 imerabox kernel: [ 1.595567] usb 5-1: New USB device found, idVendor=046d, idProduct=08d7
Mar 20 08:43:39 imerabox kernel: [ 1.595571] usb 5-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
Mar 20 08:43:39 imerabox kernel: [ 1.941120] usb 9-1: new low-speed USB device number 2 using uhci_hcd
Mar 20 08:43:39 imerabox kernel: [ 2.112522] usb 9-1: New USB device found, idVendor=045e, idProduct=00db
Mar 20 08:43:39 imerabox kernel: [ 2.112525] usb 9-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
Mar 20 08:43:39 imerabox kernel: [ 2.112527] usb 9-1: Product: Natural® Ergonomic Keyboard 4000
Mar 20 08:43:39 imerabox kernel: [ 2.112529] usb 9-1: Manufacturer: Microsoft
Mar 20 08:43:39 imerabox kernel: [ 2.120099] generic-usb 0003:04A9:10A8.0001: hiddev0,hidraw0: USB HID v1.10 Device [Canon iP6220D] on usb-0000:00:1a.7-3/input2
Mar 20 08:43:39 imerabox kernel: [ 2.120176] usbcore: registered new interface driver usbhid
Mar 20 08:43:39 imerabox kernel: [ 2.120178] usbhid: USB HID core driver
Mar 20 08:43:39 imerabox kernel: [ 10.774998] scsi18 : usb-storage 3-3:1.1
Mar 20 08:43:39 imerabox kernel: [ 10.775062] usbcore: registered new interface driver usb-storage
Mar 20 08:43:39 imerabox kernel: [ 10.788078] input: Microsoft Natural® Ergonomic Keyboard 4000 as /devices/pci0000:00/0000:00:1d.1/usb9/9-1/9-1:1.0/input/input0
Mar 20 08:43:39 imerabox kernel: [ 10.788109] microsoft 0003:045E:00DB.0002: input,hidraw1: USB HID v1.11 Keyboard [Microsoft Natural® Ergonomic Keyboard 4000] on usb-0000:00:1d.1-1/input0
Mar 20 08:43:39 imerabox kernel: [ 10.812051] input: Microsoft Natural® Ergonomic Keyboard 4000 as /devices/pci0000:00/0000:00:1d.1/usb9/9-1/9-1:1.1/input/input1
Mar 20 08:43:39 imerabox kernel: [ 10.812156] microsoft 0003:045E:00DB.0003: input,hidraw2: USB HID v1.11 Device [Microsoft Natural® Ergonomic Keyboard 4000] on usb-0000:00:1d.1-1/input1
Mar 20 08:43:39 imerabox kernel: [ 11.291908] usblp0: USB Bidirectional printer dev 3 if 0 alt 0 proto 2 vid 0x04A9 pid 0x10A8
Mar 20 08:43:39 imerabox kernel: [ 11.291920] usbcore: registered new interface driver usblp
Mar 20 08:43:39 imerabox kernel: [ 12.193530] input: zc3xx as /devices/pci0000:00/0000:00:1a.0/usb5/5-1/input/input18
Mar 20 08:43:39 imerabox kernel: [ 12.193835] usbcore: registered new interface driver zc3xx
Mar 20 08:43:39 imerabox kernel: [ 12.196298] usbcore: registered new interface driver snd-usb-audio
Mar 20 08:43:43 imerabox kernel: [ 20.524564] usblp0: removed
Mar 20 08:43:43 imerabox kernel: [ 20.527421] usblp0: USB Bidirectional printer dev 3 if 0 alt 0 proto 2 vid 0x04A9 pid 0x10A8
I just now plugged in a USB flash drive, and device notifier popped up as expected. Here is the system:
Host/Kernel/OS "imerabox" running Linux 3.3-0.towo.1-siduction-amd64 x86_64 [ aptosid 2011-02 Ἡμέρα - kde-lite - (201107131633) ]
CPU Info 8x Intel Core i7 950 @ 8192 KB cache flags( sse3 ht nx lm vmx ) clocked at [ 4217.159 MHz ]
Videocard nVidia GF100 [GeForce GTX 480] X.Org 1.11.4 [ 1920x1200@50.0hz ]
Network cards Marvell 88E8056 PCI-E Gigabit Ethernet Controller, at port: d800
Processes 301 | Uptime 20min | Memory 1458.8/5966.5MB | HDD OCZ-REVODRIVE,OCZ-REVODRIVE,KINGSTON SS100S2,WDC WD1002FAEX-0,WDC WD1002FAEX-0 Size 2140GB (3%used) | GLX Renderer GeForce GTX 480/PCIe/SSE2 | GLX Version 4.2.0 NVIDIA 295.20 | Client Shell | Infobash v3.37