Internet Explorer cannot open the Internet site http://mail.google.com/mail/
IE7 is one of the gmail supported browser. http://mail.google.com/support/bin/answer.py?hl=en&answer=6557
I've tried to delete the browser's cookies. It work for me at least until now (2 days) but some of my friend not working. One of the way that always work for me is click on the gmail button from google toolbar.