I have a workbook with sheets protected by passwords.  A
colleague entered a totally different password, unrelated
to this workbook, and the sheet unlocked!  A bit of
experimentation showed that even a new workbook would do
this in both Excel97 & 2000.
eg: lock a sheet with "mcc" and it can be unlocked with
both "mcc" and "aaa".
Does anyone know why - and more to the point, how do I
avoid this - "aaa" is hardly difficult to guess!