Yesterday we did make a small change to the way we handle sessions - try to delete all cookies for RHP from your computer.
If you need help with this (And Google is not helping you) post your browser type here and I'll post instructions.
Edit : Guide on how to do this here Thread 146337
Edit 2: Assuming your browser is Chrome, which does appear to be the cause of the problems.
Originally posted by RussHad problems with Firfox on MacOs X, none with Safari on OS X, none with IE or firefox on WinXP
Of course. The above problem for Chrome has not been experienced by all Chrome users, just some.
The same applies to your Firefox issue.
We didn't experience any issues at all during test.