Problem saving files from local to network

I've been all over google with this problem, and only a couple of people have posted anything like it -- no one has any idea what causes it / how to fix it:

A Sony laptop running WIN 2000 Pro and using Office XP (with Word & Excel 2002). Had a recent harddrive crash, bought a new HD, installed, everything is working just fine. One thing it's doing that it didn't before:

If you open a Word or Excel file that's on the local drive and then use File / Save As to browse to a network drive and save it in a folder on that drive, the laptop totally freezes. You can't even use Task Manager to end the task. There's no way to stop the freeze except using the power button to shut down.

Every other computer on our network can perform this function. It's not related to this user's network profile because if I use his network UC on another station, the function works. Also, if I sign onto the laptop with a different UC, the freeze still occurs. It's definitely some setting or something on the station itself. NOTE: You can use File / Save As to save the file on the local station and then copy and paste it into the network drive folder; you just can't use the File / Save As to navigate directly to the network folder and save it. It's not a matter of access to network drive/folders, because this laptop can access all network drives/folders and open files there, edit them, save them, etc..

Any ideas? I've spent HOURS in forums and even had a pretty experienced tech look at it for me. We tried lots of things with no luck.

HELP!!