Auto-unhiding of columns in shared workbooks

I have a problem with a shared workbook I use at work:

I have a number of columns within one of the sheets which contain formulas I don't want the other users to see, so I've hidden them before I shared the workbook.

What seems to be happening is when one user opens the workbook when another user already has it open, all my hidden columns unhide themselves, both users then save their changes with the columns unhidden so if I want to hide them again I have to get every other user out, manually hide all of the columns and save changes before any other user has chance to open it again.

Any suggestions as to what is causing this and what I can do to prevent it?

Hi,

I'm not too familiar with all the rules surrounding shared workbooks, and by definition it's not possible to test this aspect on a non networked PC. However you could try putting the hide columns macro - assuming you have one of course, in the Workbook_Open event.

In addition what about unlocking cells in those columns that other users may see, hiding your columns and protecting the sheet. Does this prevent the sheet being activated with the hidden columns made visible?

HTH