Exell97/2000 hangs when opening file

I have a user who’s PC is running Windows NT 4.0 (SP6a) with Office 97. When opening file
in Excel, computer hangs, or it takes 4 minutes to load a file (from server). This does not happen in any other software package loaded onto the PC, only Excel. I have tried re-installing all the software again and updating sr 1 and 2 but with no luck.
Same thing happend another user, who’s Pc is running Windows 2000 (Sp1) with office 2000. All other machines works just fine. Any suggestions for an very stressed Finnish It.