Actually, I have found that I prefer Firebird, which is also a Mozilla borwser, over plain Mozilla. And I definately prefer it over IE6. Opera is another browser that works very well, but personally I find it too cluttered for my taste (just a personal opinion).
Firebird does almost every thing I could want it to do, except on two web site I go to, and then I have to go back to IE6 to use them.
If you are adamant about using IE, then perhaps you could try re installing it from your systems cd, and that might cure your hang up problem.
When did this problem first manifest itself? Was it just after you installed any new hardware, or software? Did you make any major changes in your operating system? Have you kept current on all the msn upgrades and updates?
Good luck in your search for the problem.