Have you ever been modifying the view of a web part when all of sudden the page crashes with no warning and no advice on how to fix it? I hate when that happens.
The solution, add ‘?contents=1’ to the end of the page url and it will open in Web Part Maintenance view. Delete the suspect web part, then try to reopen the page. It should open and work properly without the web part in question. You can then add the web part back to the page, and continue troubleshooting.