Excel is not totally safe from hackers and password crackers, but for your
normal users, you do the best you can. Yes, a Workbook_Open event can be
used to check today's date against the workbook's last modified date or
created date or a date 7 days prior to today, and then run your WS.Protect
code. Even that can be circumvented if a user were to change the computer
date back in time. You do the best you can. Also, you can password protect
your VBA code so the modules are not visible without a password. In the VBA
editor window under Tools/VBAProject Properties, there is a protection tab
to lock out code from being viewed.

Mike F
"Robert Crandal" wrote in message
...
I would like to setup my spreadsheet so that a user
cannot change the data after 1 week. What would be
a good way to block users from changing their own
data after 1 week or longer???

I figure, I can processed Workbook_Open() and test
how old the workbook is. From this point, is it simply
good enough to password protect the sheet???

I am not completely confident that the "Sheet Protect"
mechanism is completely secure, I mean, can't a skillful
user open up the VBA editor and write code to change
data on the protected sheet???