How to have only one instance of a workbook open at a time

[derekg]

I am writing an estimating tool for window repair. To avoid confused workers (some of whom are not too computer savvy) I would like to only allow one instance of the workbook to run at a time.
What VBA code would work for this.
Thanks
derekg

 

[derekg]

GTO,
Your coding ability and knowledge of vba far outstrips this simple brain of mine. all I can answer is that this code works for me in 2007 and I get an a message box that would probably stop even simpler minds from opening and overwriting their work.

Keep not thinking (to much) works for me

thanks for the input
Derekg