Add-In UserForm Crash
 

I have an Excel 2000 Add-In that I created using VBA and a standard userform.
The Add-In adds a button on the Standard toolbar. The button simply invokes
the userform:

ufmain.show

The ufMain form has some code in the UserForm_Initialize and
UserForm_Activate subs.

I've compiled the code for this Add-In and tested the Add-In on my office
computer (Windows 2000 Prof, Office 2000) and at home (Win XP, Office XP). I
have no problems running this code in both of these environments.

I've distributed the code to the users, and they've installed the Add-In.
When they press the command button on the toolbar, Excel simply goes away....
aborts with no error message or indication as to why.

I originally locked the add-in code with a password, but opening up the
password doesn't seem to solve the problem. There are no errors left in the
application log in Windows.

Any ideas what's happening here?