Delays when using a PC not connected to Domain

I'm running Vista business on a Fujitsu tablet connectde to a Domain. When
I'm not on the domain it uses cached credentials.

However whenevr I try to "open" a file or "save as" and I get a dialog box
to select from, or input my file name, the dialog box appears and then I have
to wait 20-30 seconds before I can take any action as the system must first
time-out on Network domain drives.

There must be some system setting where Vista can be told (kind of
ridiculous because this isn't a problem with XP) not tro look for network
drives - but I can't find anything.

Thanks
Luke