I have ppa:cr3/ppa in my sources list. It upgrades my checkbox, checkbox-gtk и checkbox-qt packeges to version 0.14~ppa6.12.04 . And now I have problems with updating system, and sometimes critycal system errors.

I tried to use ppa-purge to downgrade them - it didn't work. I tried to delete them from synaptic - it want's to delete ubuntu-desktop with them.

When I try to update system I'm getting an error:

checkbox checkbox-gtk checkbox-qt E: Sub-process /usr/bin/dpkg returned an error code (1)

How can I solve this problem?