Has there been some changes to security for XP in some of the latest security patches for XP??

I get a "Access to the registry key HKEY_CLASSES_ROOT\MYAPP is denied" error no matter what I do!!!

My System is:

a. Win XP Professional all latest security fixes;
b. Visual Studio .NET 2003

I have tried the following all to no avail:

a. In machine.config run the asp.net process as SYSTEM account - didn't work (it ran as SYSTEM, but still same error)
b. In machine.config run the asp.net as a privelaged user with admin rights- didn't work (it ran as SYSTEM, but still same error)
c. In component services, reduce security to nothing - still same error

I can write a Remoting wrapper around the COM+ service, but that makes no sense, as now I will have to do 2 hops, i.e. One from ASP.NET app to Remoting Server, and then DCOM from remoting server to DLLHost!!

Anybody know how to fix this???

Thanx