Site lockup using Exploer 8 Vista Premium or XP pro

Every time I log in I try to move around the page the system locks up. If I let the page sit it will eventually bring up error box
Windows Internet Explorer
Stop running this scrip?
A script on this page is causing Internet Explorer to run slowly.
If it continues to run your Computer might become unresponsive
YES or NO choice boxes.
Is this an Explorer 8 issue? I have the same problem with my HP with Vista or IBM with XP pro.