I am experiencing two really strange things in an Add-In I've created,
one additional note is that the following problems are only occurring
on a handful of machines out of about 100 where it has been

First one is a simple setting a new instance of a class

Set myObj = New ClassName

If I do a F8 in debug mode on this line the whole of Excel closes and
does its auto restart, I have run this code on two machines side by
side and one works and other other doesn't.

The second problem is that a function calls from a module into a class
in not going into the function, it basically goes somewhere completely
different, into code that is not even being called. Same scenario as
above with both machines, one works and the other doesn't. I am
referencing some custom built COM dll's.

This is extremely wired behaviour and I have no idea why this could be
happening? Anybody have any thought?

Thanks, Rick