The first step in troubleshooting this issue is to run Internet Explorer in "No Add-ons" mode. Here's how you do it.
Go to Start, All Programs and System Tools
Click Internet Explorer (No Add-ons)
Restart Internet Explorer. If it runs smoothly, then it can be determined that one of the add-ons was causing the problem. You will need to continue troubleshooting this issue until you find out which add on was causing the problem.
Start Internet Explorer 7
Go to Tools, Programs, Manage Add-ons button
Under the option "Add-ons that have been used by Internet Explorer", you will see a list of all of the add-ons installed on your system.
Click the name of an enabled add-on and then click Disable under the Settings option.
Note: You may want to speed this process by disabling 3 or more add-ons at a time.
How to reinstall or repair Internet Explorer in Windows XP
http://support.microsoft.com/kb/318378