Can't set Outlook Express as the default mail client

[WayneM]

I am using a VB6 program to send email, using Outlook Express. I am trying
to run this app under a service that automatically starts it. The problem
seems to be that the Service runs under a different logon than the one that
set up Outlook Express. When I logon as the user that runs the service I
cannot set Outlook Expresss to be the default mail client.

I tried setting the Option in Outlook Express, but it doesn't seem to work.
When I close Outlook and reopen it, Outlook warns me that it is not the
default client. When I click Yes to that question that doesn't work either.

Finally I opened IE6 and tried to set Outlook as the default mail client,
but Outlook Express was not in the list of available clients, just regular
Outlook and Hotmail.

Any suggestions on how to set Outlook to be the default?

Thanks in advance,

WayneM