This could possibly be the problem, I'll have to do a check with the user as soon as possible.

One thing I noticed was that on my PC, the file does work fine. However, I am using Office 2003 and the MSCOMCTL.OCX file is not up-to-date.

My colleague beside me can also open the file, and he is using Office 2010. His MSCOMCTL.OCX is up-to-date.

The user who has been having the problem, has Office 2010 and his MSCOMCTL.OCX file isn't up-to-date, I'll see if I can update this. So I'm wondering if it is to do with the MSCOMCTL.OCX file and Office 2010?

I will let you know the outcome.