That's why I posted here, there is no clear cut reason for the error :{ In fact most of the info I found relating to that error related to some bug in IE3 :}

There is possibly some other processes on the machines that are causing the errors but my indication that it was Win2K specific was based on tests of about a dozen machines here.

I am not using threading or forking, it's a monolithic program.

I've seen hints at suggestions of trying to authenticate to the machine before trying the Registry operation and I'll try running the program as the Domain Admin and see if that helps.

Now that I've been pointed down the authentication track, it makes sense to connect as a power user (domain Admin or such) to the machines.

With WMI, I can specify the user to connect as (Domain Admin) but with the registry probe, I'm attemtping to connect as an ordinary user.

Thanks for the suggestions!

Kakaze