Redirect?

HI i have a user that has a redirect on there domain, there index.html files redirects people to the forums/ directory. When they try to loginto the control panel it trys to redirect them to the forum it comes up with the error

Not Found

The server was not able to find the document (./forums/) you requested
Please check the url and try again. You might also want to report
this error to your webhost.

Can Anyone help me solve this?