I might have a sollution:

install pidgin protocol for conversations and contacts
Now it is possible to delete the other conversations and contacts plugin.

second of all, don't use that plugin anymore. It's bufferfly's wich has ALOT of bugs. I had almost the same thing...

Couldn't delete plugins for C&C etc. Cause all the plugins needs eachother I guess...

So if you can delete the plugins, delete pidgin also... so you don't have any plugin left for C&C. then just download the pidgin again.

Worked for me... But can't guarantee.

Good luck!