Windows XP, SP2, with all updates.
Error message started after first installation of this version. But since it had disappeared after some time, I did not worry so much. Now it comes back from time to time. And when it comes, there is no other way to go on than to put a cdrom into the drive.
In the meantime I found out, what triggers the error message.
When I have used a cdrom in my drive BEFORE using spybot, I get the error message, when starting spybot (with cdrom removed).
Of course there is no error message, when I let the cdrom in the drive.
regards