This is an NT 4 domain? SMB signing on the workstation end is the usual culprit, but that doesn't jive with it working with a Domain Admin account. Is there any sort of error message on the workstation, or a security event on the DC?

I would double-check Q281648 and then make it PSS's problem (assuming that you have a support contract).

Aside: My company switched to Gateway due to a publicized battle we had with Dell. I imagine our Gateway sales rep is about the only person satisfied with the deal. I decided that I'd buy my own damned laptop once my Inspiron was too obsolete.