I have a user who is getting the above error when trying to access network shares via a mapped drive(s).
Prior to me seeing the issue she has changed her password. I have also reset her password again since from the small business server 2003 which runs the site.
I have noticed whilst logging in and out using her domain account that I get a message saying the account is locked out too. I have discovered that after initially managing to log in the account becomes "locked out" in AD. There is a tick in the relevant box in the users accounts tab in AD.
After the user logs in successfully I can go in and untick this account lock check box. The user then gets a different message when trying to access the share -"unknown username or bad password".
This same user is able to login to a different PC and access the shares no problem. I have just upgraded the troublesome PC with XP SP3 since discovering this issue but that didnt help. Although during the installation of the service pack (I installed it under the users account) I noticed that I was able to access the shared drives OK.