Ran into a problem after modifying a web part. Could not open the default page for my SharePoint site. All other pages worked fine. Found a gem online that saved me. Add "?contents=1" to the end of the URL. For example, http://mysite/default.aspx?contents=1 . This will give you a list of webparts on that page and allow you to delete the one you suspect is causing the problem. Worked great for me.