10.04 Strange screen on shut down

[Silvertones]

After clicking on the shut down button a small window flashes by. I can't see what it says. Anyone know what this may be? I tried to screen capture it. It's a maybe 2"x4" graphical screen.
My CC was hacked so now I'm parnoid. I never install anything on this machine that doesn't come from the repos.
Thanms!!!

[Silvertones]

Someone must have an idea. I tried googling and it appears that this sometimes happens at startup but can't find it at shutdown. More testing shows that it only happens if I've been using Firefox. Sometimes also in the task bar is an "untitled window".
If I could capture it at least to see what it is. How can I capture this after I've clicked "shutdown" Is there a way to see what may be running.
Please help.
Thanks