I have created a spreadsheet containing VBA code that I want to distribute
to customers. In order to let me run VBA on clients' machines, I have bought
a digital signature and have signed my file.

My problem is that the code needs to create new worksheets, but if I save
the file after doing so, Excel complains and drops the signature with the
error message "You have modified a signed project. You do not have the
correct key to sign this project. The signature will be discarded."

I think this arises because the new worksheet generates a corresponding new
'Microsoft Excel Object' - i.e. Sheetx, and that VBA then considers this
amounts to changing the macros and therefore requires them to be re-signed.
My question - is this correct and if so, are there any workarounds?

Thanks

Luke



Background information

- version : Excel 2003. Upgrading to 2007 is a possibility if it overcomes
the problem.

Other questions

Having read around the problem, I seem to have two options:- force users to
run macro security at low, or modify my code to run as an Excel Addin file.
I've never had to do either before, so

- Can I set a user's macro security level programmatically?
- If I went for the add-in approach, what would I lose? My workbook is
currently very interactive, with Macros running on some Change and Select
events; would that have to go?