Hi Mark,

You may alreday have discovered the reason for this behaviour. In case
you have not, this may help. I experienced the same problem with
another ActiveX that stopped working when compiled with VS 2008 and
tried to run on Vista. My investigation found that the failure only
occurs if:

1. The application that uses the ActiveX is compiled with VS 2008
AND
2. The machine that is running Vista has Data Execution Protection
switched on
AND
3. The machine's CPU implements the DEP

If I switch DEP off using the following procedure then the ActiveX
works fine:

Run a command prompt as administrator. From the start menu, select
"All Programs", then "Accessories" and right-click on the "Command
Prompt" shortcut and choose "Run As Administrator". From here you can
use the following command to disable Data Execution Prevention (DEP)
with the following command:

bcdedit.exe /set {current} nx AlwaysOff

I found the above at http://www.realtime-vista.com/administration/2007/04/disabling_data_execution_pr
eve.htm
I am not sure if this solution would be acceptable to all our
customers!

Regards,
Joginder Nahil
www.starprint2000.com