You should try loading IE8 without any add-ons enabled to see if the problem is with IE8 itself, or if the problem is with a conflicting add-on.
If I recall correctly, the way to do this is from your Start menu at;Programs
-> System Tools
-> Internet Explorer (no Add-ons)
This should load IE8 with no add-ons enabled. Let me know if that fixes the problem.
If it does, you'll have to begin disabling add-ons one at a time to see which one is causing the problem, but we'll cross that bridge when we get to it.