Optional fix.
Additionally you can try this fix if that doesn't work for you. I've had a winxp computer that magic disc has worked fine on, and then one where it didn't. Had issues with 64-bit vista particularly... I switched to Daemon, the only thing is I liked how it didn't have to restart the computer to install. Very nice for school computers when you want to run a disc emulator, but they have Deepfreeze or similar things preventing installation of programs that require a restart.
Anyhow:
1. Open Regedit (windows key + R = runbox, type in regedit.exe)
2. Search for 'mcdbus'. Delete the entire folder (should be like HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\mcdbus)
3. Search again. Delete this one too (should be something like HKEY_LOCAL_MACHINE\SYSTEM\ControlSet003\Services\mcdbus). Note you may wish to actually export both of the above first, just in case.
4. Reboot the system.
5. Ignore the error that comes up on startup due to failed driver load. (if it does)
6. Open Task Manager (ctrl+shift+esc), make sure you don't have mcbus.exe running, if it is kill the process.
7. Run the uninstaller again.
8. If that fails as well, try just deleting Magic Disc folder's entire contents, (with it removed with regedit, you should have permission, make sure you are an administrator on the computer.) Also make sure you deleted the driver mcbus.sys (in main sys32 drivers folder, as indicated above).
Here for more information:
http://www.blakjak.net/node/1042
Why would you disable such a life saving feature?
I disable it on computers with 512mb or less ram, it just takes up too many system resources for such a computer. I back up important files regularly onto a network server, as well as a removable disc drive, so I'm not that worried if I really do have to reformat and reinstall windows. It only takes 30+ minutes tops, especially with the nice batch file I have that installs all the programs and gets all the windows updates I want, without user intervention.