To disable the background channel scanner:
You can try this alternative reg fix, rather than renaming mcglidhost - create the reg key below and give it a value of 0
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\MediaCenter\Service\BackgroundScanner\PeriodicScanEnabled
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\MediaCenter\Service\BackgroundScanner\PeriodicScanEnabled
It actually does do an automatic background scan of digital channels (Clear-QAM, and ATSC.)
PeriodicScanEnabled (if it's not there, create it (as a DWORD value) in that folder), and set the ValueData to 0. (for future reference: 0= disabled; 1= enabled.)
Close Regedit, and reboot.
Required warning on the BackgroundChannelScanner: you cannot run TV Setup (when you're using digital (Clear-QAM and/or ATSC) tuners with this service disabled. If it is disabled, TV Setup will fail (hard-lock) on the 'scan for additional channels you may receive' portion of setup. If you need to re-run TV Setup, you must first enable the service.
If this fixes your issue, great. If it doesn't, you can always re-enable the service (just set it to 1), and we can try something else.