I am running an Auto_Open macro which calls up a password Dialogbox. If the
person has the correct password they can open and edit the workbook. If they
do not have the correct password, they must be able to open and view the
document but not be able to make any changes.

What I need is something which will open the Workbook as Read Only and all
cells on all worksheets locked.

I know that by opening the workbook as read only they would not be able to
over write my original workbook but they would still be able to make changes
and print those changes. I also know that if I allow the workbook to open
(not Read Only) and lock all the cells through the Macro they could then
same the workbook and then all the cells would be locked next time it was
opened. I have some cells which are normally locked so even for normal usage
worksheet protection is turned on.