Documents Corrupting

The system we have at the moment is
Various PCs ranging from 700MHz-2.6GHz, with 256MB to 512MB

One site has NT4 SP6 running Office 2000
Documents held on Compaq servers running Advanced Server 2003 -Active Directory.

There have been numerous occasions were varioous users have openned known good copies of Word documents
(Open/save/close fine on PCs in other sites)
for them to be faced with hieroglyphics.

Any ideas?