Vista - Cannot log onto user profile when away from network domain

A "new Vista user" question:

I manage some computers for sales reps that connect to our business network
50% of the time, but then take their work on the road with them. With
Windows XPSP2, the user could access his "company.com\username" profile,
whether he was attached to the network or not.

I'm now testing a setup for a sales rep on a new Vista machine that I set up
at work - where I set up a user profile for the sales rep when connected to
the company network (i.e.., Log onto company.com).

Now, when I'm connecting this user in a home environment, and attempting to
access the same company.com\username profile, I get a CREDENTIAL MANAGER
LOGON WIZARD error message that reads "There are currently no logon servers
available to service the logon request" (which is logical, he wouldn't be on
the network).

XP SP2 still let you log in to access this user profile anyway -- you just
didn't have access to network resources that you weren't connected to. I'm
hoping to find a way to provide the same user experience in Vista.

I haven't (and don't know how) to change credential manager options to allow
this - but hope that there is a way to do so. Forcing our remote sales reps
to log onto one profile for work, and another when away, would not be an
elegant option - I'd strongly prefer for the user to keep the same profile
both on and off the company's network.

Is there a way to do this?
--
pbrill1