Can't login from one computer

Hello,

I have an IMAC with both Safari and Firefox installed. This is my primary system for working on my sites – and have never had a problem before.

When I try to login to my site it just brings me right back to the login page – using either Firefox or Safari, the same thing happens.

If I register as a new user on the site, and then try to login using the new user credentials, the same thing happens.

Yet everything seems to work fine from my other systems – had a friend try logging on, he had no problems……nothing was changed, installed, removed, or added since it last worked yesterday. I cleared the cache, deleted the cookies, etc….it seems specific to this machine and not the brower. I’ve rebooted the router….

Any ideas???

Thanks!
Ropb