TSM/ADSM backup problems, possible causes?

I have a TSM setup on RS/6000 talking with a tape library and
for all machines but one this works fine. One Windows 2000 box
takes over four hours to backup 5GB. An identical machine, same
applications (file server), same network card, same os, same patches,
same agent, same network settings, same dsm.opt, same everything
I can think of checking, takes the same mount of time but backs
up 60GB of data.

What else can I check here to find the difference and eventual
problem? Also journalling does work on the successful box, but
not on the failing box.

Mike