Firefox Crashes

I am using Firefox 3.0.6 and it constantly crashes. I get the following error code:
Add-ons: {972ce4c6-7e08-4474-a285-3208198ce6fd}:3.0.6
BuildID: 2009011912
CrashTime: 1235171248
InstallTime: 1235171093
Notes:
Obj-C Exception data:
NSInternalInconsistencyException: Error (1000) creating CGSWindow
ProductName: Firefox
StartupTime: 1235171205
Theme: classic/1.0
URL: http://www.google.com/ig
Vendor: Mozilla
Version: 3.0.6

When I downgrade to Firefox 2 it works fine, but I'd rather use 3.0.6. I'm not really sure what to do; I've tried purging all references to Firefox and then reinstalling, but the error keeps happening. I may be missing something though. The error mostly happening when navigating the menus, but also happens randomly, each time with that same error code (1000). The error started with my bookmarks folder, and the browser crashed every time i tried to open it but I fixed that via mozilla's troubleshooting recommendations. Hopefully it's something to do with Firefox as opposed to my OS X version (10.5.6). I'm on a new macbook pro, by the way.