The exact same thing has just happened to me. At first my password also wasn't recognised so I had to change that on the account management part of the site. Now I have the same issue, can log into the viewer but get an 'POL-5132' error, problems with mail/contacts and crashes to desktop when I try to play it.
Strangely it started with the game crashing to desktop with a 'server error' followed by an automatic 'update' through Steam.
EDIT: I have also tried the file check from the viewer, no errors found there.