Maybe that has the same cause as the error I've seen few times - sometimes when I click on my wallet, nothing happens, but when I clear browser cache, then it starts working.

Try clearing the browser cache (in Firefox it is Edit -> Preferences -> Advanced -> Network and press "Clear now" there) after logging in, I guess in some situation there are some data from previous unauthenticated state (before you've logged in) that are messing with some functions, or maybe incorrectly returning you back to page from where you've logged in.