Gmail uses JavaScript to allow you to login. However, a lot of programs, including privacy control programs from McAfee, Symantec and Zone Labs, can interfere with it, if they're set to block scripts on all pages. The best thing to do is to post what AV/firewall software you have so that we can guide you to check for the appropriate settings. Usually, you will need to either Gmail in the safe/accepted list or to be a little less paranoid and accept/allow scripts on a selective basis rather than blocking them completely. The solutions wouldn't work unless you somehow found a way to allow the scripts to run.