Okay
Is it strictly speaking a "blank page" or "about Blank" page, the first is easily fixed by setting a home page or choosing one of your favorites, the second one could very well be CWShredder How to Remove both can be confusing....
To set your home page go into internet options, it should show you a window where you can set your home page, and if you look there is one there that when set will open at about:blank (use Blank)(can cause confusion about highjackers) it will then load as about:blank in the URL and show a completely white page, but even so you should still be able to open from your favorites, if you can't this leads me to believe it's a redirect of some sort???
If you are able to use another browser then your internet settings seem okay, like nihil mentions go ahead and clear out your cache and cookies.
What version of IE are you using, do you have the latest security patches for it, you can go and download the newest IE7 Beta (it's beta so be wary)...and this may fix the problem...IE7 Beta Preview
Oh just had another thought...check your "proxy settings" sometimes when I don't want users to use IE, I will set a phony proxy address, and each time they try to access the internet, they get a blank page...go to options/connections/lan settings, and see if there is an IP in the proxy server settings.