Users suddenly able to modify the same documents at the same time.
 

We have a group of 4 investers sharing a set of spreadsheets. All of a
sudden yesterday they were all able to open the documents at the same time
without getting the messages about "read only" because it was open by another
user. Today everything is back to normal.

No network changes, and the documents are set correctly (i.e. not checked)
in Share Workbook.

Help!!! This is the group that always has problems nobody else experiences,
and somehow they always believe "something changed on the network".

- Can the "share workbook" be applied to the whole program rather than a
document?
- Any thoughts, any at all, as to what may cause this?

2 users: WinXP Office 2000
1 user: WinXP Office XP
1 user: Win98 Office 97 (yeah, I know)

Thanks!!