[xubuntu] Crash on unmounting external drives

I'm not sure if it's really a crash but it sure does look like it.

This never happened on my 9.04 Ubuntu before. I chose to install Xubuntu 12.04 since it's much lighter and I expected it to work better on my EeePC 701.

The problem is that this happens whenever I try unmounting external drives. It doesn't exactly happen all the time but it happens every once in a while. Quite annoying, really.

I've taken pictures of what happens...

http://fc05.deviantart.net/fs70/i/20...ae-d5gjcyj.jpg

http://fc02.deviantart.net/fs70/i/20...ae-d5gjct1.jpg

http://fc09.deviantart.net/fs70/i/20...ae-d5gjcgb.jpg

How do I fix this? Or, at least, what causes this so I can avoid it?