AB2012: 2. Some of the simpler disc checks merely detected if a drive appeared optical and / or had a certain volume name. These simple checks often couldn't tell the difference between an actual disc in an actual optical drive, vs a virtual optical drive mounted from a backed up .ISO file of the disc using software like Virtual CloneDrive, DAEMON Tools, etc, which basically faked a "pass" for a disc check without even patching the disc check out.