python-twisted unmet dependencies

[bad_aptitude]

After a du yesterday I had an error about unmet dependencies for "python-twisted". So far my system seems to be working. Though debian package search doesn't run - which based on another post appears to be a different issue.
I re-ran the du  again this morning and the unmet dependencies are still there.
bad_

[bad_aptitude]

another perhaps more disturbing observation after my last du.
I now get the following warning after apt-get update
'W: No sandbox user '_apt' on the system, can not drop privileges'