You're not using Peerguardian are you? I've had the same problems with Firefox (and IE not loading some pages as well), but when I quite Peerguardian it works fine.
If not, have a look at what else you have running eg. firewall, anti-virus, etc. as it could be something like that which is conflicting the way peerguardian is with me. Obviously you don't want to be switching off a firewall or anti-virus software when browsing, but it may help to try briefly to see if something like that is at fault.

Using SP2, windows XP. Not loading with IE, Opear and Firefox. Had Netscape too, but the same, wont work. Can't post long replies, becuase I will get the error
With msn explorer, I can view the inbox, but it was all messed up, and not loaded properly etc... If you can help me, and want some info about what I'm running etc ask me, thanks. 
