How to find out what program has crashed

[ampakine]

I'm on ubuntu and every now and again something happens and the graphical interface becomes unresponsive. Sometimes it all out crashed and I can't even move the mouse pointer but other times its just the firefox and/or nautilus becomes unresponsive to mouse clicks but I can still use Alt + F2 and run programs or Alt + Tab to switch between windows etc. On a couple of occasions the computer was more or less completely frozen for about 15 minutes then I get a message telling me that a javascript script is not responding and gives me the option of force quitting it and after I quit it the computer goes back to normal so I suspect that these crashes are always caused by a program not responding. How can I find out what program is not? I hate forcefully shutting down my laptop cuz this sometimes results in me not being able to mount the harddrive but when it locks up like that I don't know what else to do. If I knew what process was causing the problem I could kill it though. Anyone know how to find out what program is not responding? Preferably with the command line because most of the GUI usually freezes when this happens.

[fashizzlepop]

It sounds like Firefox's JavaScript engine is shittin out on you. Try using Chromium.

[tgoe]

Steps to reproduce the problem? Also, give Opera a try... so cash...