What could have caused this X problem?
 

I was browsing around with Firefox in XFCE and tried to download a file then firefox closed all by itself. It happend when chose the directory to save the file to. Tried again, and Firefox shutdown again. I killed X then logged back in the same user but in KDE and tried the same exact thing and got the same results except KDE gave me a message saying cannot execute protocol to open that location to save a file to. Firefox crashes/shuts down when I choose the file save location. A reboot fixed the problem, not just killing X. Has anyone experienced anything like this? and what kind of nethack would do this?

P.S. This is unrelated to my other posts about firefox. :)