Problems with buttons

[Q]

Hi everyone

I upgraded to 11.10 a couple of weeks ago and so far have found 
everything to be fine apart from one little niggle: buttons in certain 
applications don't work at all.

It seems to be system-related apps. For instance, in Synaptic, I can't 
add new repositories because the Add button on the Repositories dialogue 
box just doesn't do anything (not even the animation that it has been 
clicked). The Close button on the dialogue doesn't work either.

Just this morning, the Update Manager alerted me of updates, but the 
Install Updates and Close buttons didn't work (although the Check one 
did). When I opened up the Update Manager from the menu, the Install 
Updates button worked fine, but the Close one didn't once the updates 
were done.

I think I've had problems with other system apps as well, but I can't 
remember what those were off the top of my head.

It's rather annoying, especially not being able to add repos through 
Synaptic. What's going wrong? How do I fix it?

Thanks in advance

Q