Trouble joining a domain? (MSWin)

Strange; this has happened more than a few times now, so time to expose my ignorance:

• We have a Citrix server running on Win2K3 Server.
  
• It's configured to bind to a domain in order to allow use of the accounts there.
  
• The PDC is on a Mac OS X Server box (10.4.11).
  

The initial bind is fine and authentication works great - until it breaks.

When it breaks, simply re-entering the info yields a 1326 error; it thinks the credentials are wrong. It seems there may be some caching of credentials, though I haven't found where or how to flush; rebooting the Citrix server doesn't help.

It also doesn't help to re-bind to a workgroup, reboot, and then attempt to re-bind to the domain - same error.

What does seem to fix it is this:

• On the PDC, rename the domain & save.
  
• On the domain client, confirm a bind to new/different domain.
  Rename the domain back to the original. (On the PDC.)
  
• Confirm a bind to the original domain. (On the domain client.)
  

Theory: Caching is forced to flush by temporarily binding to another domain - we've only got one, hence the rename; it's probably not necessary if you've another domain to temporarily bind to.

(Update: If it's an option in your situation, a simple restart of the PDC may suffice.)