by Ken Task.
Version ... login to site. Go to Site Admin Menu, Notifications. Version shows there.
IF running version 2.x of Moodle, could be the cache is a little messed up. Can re-fresh the cache by going to http://site/admin/purgecaches.php after logging on as an admin level user. IF running 1.9 there is no such script and would advise turning on debugging to see if Moodle reports anything.
Since you're running Windows ... did you update anything Windows related? Like IE? Uhhh, does FireFox work?
'spirit of sharing', Ken