The first thing I would try is to delete all settings and restart pidgin.
The settings are probably stored in a catalogue called .purple in your home folder (I'm not on a system where I can check this at the moment, get back to me if you cant find them, and I'll look into it.) Notice that you need to enable
view -> show hidden files
in the nautilus menu (your file browser) in order to see the hidden settings files (in case you're not using the terminal of course).
Simply rename this directory to .purple-backup or something, so you can easily restore if it would cause some problem. Normally pidgin will just create a new settings folder with fresh settings in it. (Note that this will remove all your pidgin settings, not just for your google account.)
If something goes terribly wrong you just remove the newly created directory, and switch the name of .purple-backup back to .purple, and everything will be like before again.
If that doesn't work you can try Empathy, which replaces Pidgin in the latest Gnome.