This can only be done using VB code, ie Macro's. It's easily possible to
force the user to enable Macro's on opening by making the file useless if
it's opened with Macro's disabled. This can be done by hiding all worksheets
except one with a title or warning message. Other hidden sheets can be
displayed (or not according to the entry level you chose) by unhiding them
with code if the correct password is entered.
You should note though that Excel protection is weak and any password
including the password to prevent the viewing of VB code can be easily
broken by anyone with a little knowledge and the will to do so. It is
therefore only suitable in a security sense for casual users and definitely
not for sensitive data.
Regards,
Alan.

"EZdoesIT" wrote in message
...
In Excel 2003, I need to simulate a "login/logout" function within Excel
document, without requiring user intervention, preferably through
Login/password pop-up screen. Based on the login information (match of
user/password with predefined values within the workbook), content of
specific cells / sheets may / may not be displayed. One feature of this
login/logout function will be also to remove the content of specific cells
(where password was stored). User cannot be relied upon to 1) authorize
macros to be run and 2) to execute macro manually. Document will be used
internally so security needs are medium.