I don't use Chrome, but you may an issue with DPR cookies in FF. I suggest that you delete the DPR cookies and login again, see if that solves the problem in FF.
In FF, go to Tools > Options > Privacy > remove individual cookies. You'll next see a window with the various sites & cookies installed in FF, highlight dpreview.com then on the bottom of the page click on "remove cookies. You can (may have to) click on dpreview.com and put a check in the box for each cookie.
It might work if there is a bad cookie.