Windows – Vista / Windows Server 2003 Mapped Drive Logon Failure

I have a Windows Vista (Ultimate) machine which connects to a Windows Server 2003 machine for just one thing: a mapped network drive.

There is a user account on the Server machine which exactly matches the user name & password on the Vista machine.

The problem is… when I try to connect (map) the network drive, a message comes up saying the user name or password was incorrect! Since it then gives you the opportunity to re-enter the user name and password, I re-enter the password (exactly the same, again) and it works and the drive gets mapped.

BUT… the plot thickens! After a reboot (or, I suppose, a log-off and log-on), the network drive doesn't work anymore – double clicking it gives a short delay, and then a message saying the drive can't be reconnected because the account has been locked out. Sure enough, checking on the server shows the account locked out. A glance at the event log shows repeated "invalid password" events before the account is eventually locked out.

The specific events that are recorded are:

• A logon attempt by MICROSOFT_AUTHENTICATION_PACKAGE_V1_0, which fails with code 0xC0000234
• A "logon failure" event which says "unknown user name or bad password."
  • The user name specified in the event is the user name I'm using
  • The "logon type" is "3"
  • The logon process is "NtLmSsp"
  • The authentication package is NTLM

Both machines are using the same LAN manager authentication method (specifically, "Send LM & NTLM, use NTLMv2 session security if negotiated") – set via security policy.

The Vista machine is not part of the domain, but the user name and password match.

The Vista machine used to work just fine, back when it was an XP machine. But then, it got upgraded to Vista (not a clean re-install, an actual upgrade) and this is what happens now.

For the life of me, I cannot figure out why it seems to be sending the wrong password, when I have checked & double-checked to make sure the password is exactly the same. I've googled & googled and found nothing useful. I'm stumped!

Does anyone have any ideas as to what might be happening here – or ideas for further troubleshooting steps I can take?

UPDATE: I've tried mapping the drive via the command line and the NET USE command – but it throws up its hands as well, with a "system error 86" which says "the specified network password is not correct." Your guess is as good as mine as to what's really going on here. I wish I could sniff the actual traffic going back & forth between the computers and see what password (if any!!) is being sent…