I am struggling with this. I have one user who cannot login and only receives the username or password is incorrect. The worrying thing is I too can't login to OWA as him from outside the network or another PC.
I can't see any issues in event viewer that would suggest AD problems although I also didn't see an Audit Failure event for is login.
I have reset a spare user account and tested that can login and another user account, both of them work normally.
I have tried resetting twice and it still doesn't login with this one user?
Apart from creating him a new user account I am now at a loss?