I just installed OS Selector from Disk Director Suite 10.0. When installing it had the above error. I tried shutting down my Symantec anti-virus, Zone Alarm Firewall and Go-Back. In fact I shut down everything I could find that was in the task bar and running in the applications list. I tried to reinstall and got the same error. After retry I finally had to tell the program to Ignore. It tells me that some program is using the Disk 1 and I shoud shut it down. I tried to shut down everything but it does not tell me what program is using disk 1 . What now? The Taks manager shows no application running except the OS selector.