Password must be reset for every login

For some reason WordPress is not remembering my password. Typing in the correct password on the login page simply returns me to the login window with the password field empty. If I use the “lost password” function it allows me to go through the process of resetting the password to log in.

Every time this happens I edit my user profile and enter a new password. As soon as I close the web browser, however, the new password no longer works to get into my site. In other words, the only way I can log into my site is to use the lost password function EVERY TIME! This has been going on for months and I can’t figure out how to fix it.

I have tried this on many computers, Mac OS, Windows, Firefox, IE, Safari, etc. I have tried all the obvious stuff like resetting cache, cookies, etc.

Anyone know how to fix this??? Help!