it's very likely it's an addon that is stopping it from working, so firstly try
click start menu-> All Programs-> Accessories-> System Tools-> Internet Explorer (no Add-ons)
If that then runs then it's one of the addons stopping it from working, in which case while IE8 is running Go to tools and select Manage Add-ons and disable all add-ons, then close IE and try opening it the normal way, if that then works it was an add-on causing the problem, in which case start re-enabling them one by one (quiting IE and re-loading between each one) to see which one is causing the problem.