Meeb, am I right that the browser does execute but won't access any pages ? If so then check what the start page is set to (tools, options, home page). If the home page is one of those which klez 'blocks'*, then the browser will appear to hang. Change the start page to something innocouous or better still to blank, and see if you can get in.
* a number of AV sites and microsoft.com too IIRC.