Excel corupting files, not saving files and other problems after OS update and Tiger update

Our Office was using 10.4.7 and office 11.2.3 I ugraded all macs to
10.4.9 and Office to the latest offering via auto update (ran it until
it said nothing to update.)

Now workbooks on our server cannot be updated they can be opened but
not saved, and then once closed cannot be opened again.

Files on the desktop seem OK, has one of the security patches effected
files opened across a network?

This is a serious issue effecting our business