One thing that I've found time and time again with Windows authentication is that even though you have access to something and your password is not expired – you may still received the "access denied" type response from different applications/services.
At first you think it's some kind of issue with permissions, you try rebooting etc... But nothing works.
In these circumstances, if you have noticed that you are being reminded to change your password when you log onto the windows server/workstation – then changing your password may be the key!
It seems that although technically your account on the domain hasn't expired - because it's due to expire this sometimes seems to be interpreted as the same thing (i.e. it considers your account expired). Perhaps the underlying integrated security authentication that goes on behind the scenes doesn't always deal with this situation properly, and just rejects by default.
Anyway, try changing your password and see if that helps!
Matt.
