Hi Mojo,

Thank you for your last reply: it worked! It also works if I remove the call to "CoInitializeSecurity", so that does not seem to be related to the problem I was experiencing.

By the way, I added the missing "AppID" entries like you showed, but, until I saw your example, I was using [HKEY_LOCAL_MACHINE\Software\Classes] and your example has the entries in [HKEY_CLASSES_ROOT]. Is there a difference?

Also, it seems like a need to refresh the registry (F5) before the new entries I added are recognized: Is a "refresh" also required if I write the entries to the registry via code?

Anyway, I am very pleased that it is finally working properly: thank you for the help.