>A security issue?

Very difficult to say at this point as it could be anything.

>- Did you register the DLL as an admin (if you used regsvr32 in a CMD window, did you run the CMD window as an administrator?)

Yes, on one server I tried it, my account was an administrator. This is the account I used for registration. On the other test we did, the person also had full privileges on the PC.

>- Is the account that generates the error a local admin, or a limited user?

If was not the local admin account. My account however is part of the administrators group. Can it be that I have to switch off and use the local admin account for the registration?