Update Manager fails on fresh install

[John Seybold]

I have Parallels 8 running on Lion. I downloaded and installed "Ubuntu Linux 12.04 Desktop.pvm" from Parallels, and then installed Parallels Tools. However, when I try to run Ubuntu's Manager it says
The installation could have failed because of an error in the corresponding software package or it was cancelled in an unfriendly way. You have to repair this before you can install or remove any further software.
E:Method has died unexpectedly!,
E:Sub-process returned an error code (100), E:Method /usr/lib/apt/methods/ did not start correctly

help !

 

[John Seybold]

update: after rebooting and selecting only "Important security updates" in the Update Manager's settings and rebooting the updates apparently installed. Now when I select "Recommended updates" it looks like Update Manager might be working.

Any advice on selecting the other options for settings (proposed and backports)? They sound scary...