User Account Locked out

I have a user who VPNs from home. That account is totally different from our domain. It is from the VPN client software.
She gets into our network fine.
When she maps a drive she has to give her Windows 2000 logon account & PW.
When she discounnects from the VPN, it locks out her Windows account in Active Directory Users & Computers.
We have a mixed windows 2000/2003 network, but the DC is a 2000.
Any suggestions. I am perplexed.
thanks

What's the lockout threshold? When she tries to connect to a network server, her client is going to try the credentials she's used locally before prompting for network ones.

Seriously think about setting the lockout threshold to something relatively large -- 10, 50, even 100. If you're worried about passwords being cracked in less tries than that, your users need a lesson in how to pick better passwords. :)