Does the behavior persist in No Add-ons mode?
This post from the IE Blog will instruct you about troubleshooting Internet Explorer with Add-ons disabled - http://blogs.msdn.com/ie/archive/2006/07/25/678113.aspx
Also, this guide to solving IE 8 crashes could prove useful - http://support.microsoft.com/gp/pc_ie_intro
These might help you as well:
How to troubleshoot Internet Explorer issues in Windows Vista and in Windows XP - http://support.microsoft.com/kb/936215
How to optimize Internet Explorer - http://support.microsoft.com/kb/936213
I hope at least some of this info helps,
MSFT Internet Explorer Outreach Team