login loopback unable to access admin

Just moved my site to a dedicated server and have found I am having to reset various permissions to enable the site to run correctly. Not sure if this is the problem I am having now but I am having a recurring but intermittent login issue that occurs in both Firefox and Chrome. When attempting to login into the dashboard the login page just reloads ad nauseum. The address bar returns this –
http://mgx.com/blogs/wp-login.php?redirect_to=http%3A%2F%2Fmgx.com%2Fblogs%2Fwp-admin%2Fpost.php&reauth=1

Reloading the browsers or clearing cache can fix it and I suspect it is wp_cache contributing to the problem but I wonder if anyone can suggest a fix…
Thanks,