Microsoft have a Fix It Blog which includes simple fixes for common problems and one published today is a fix for Media Center hot key problems:
On a Windows 7-based computer, when you attempt to change channels in Windows Media Center using the Hot key function, channels may not change as expected. Using the Program Guide to change channels does work as expected.
If you have this problem you can click on the Fix It for me button on Microsoft’s fix it page, or you can fix it yourself following the steps bellow:
Let me fix it myself
To resolve this issue delete the current program guide database and allow Media Center to recreate it. To do this, follow these steps:
Close Windows Media Center
Click Start, click All Programs and then click Accessories
Right-click on Command Prompt and click Run as administrator
Type net stop ehrecvr and press Enter on your keyboard, (leave this window open when done)
Click Start, Computer and then click the drive that Windows is installed on (this is usually C:\)
Double-click the ProgramData folder, double-click Microsoft and then double-clickeHome
Click the mcepg2-0 file and press Delete on your keyboard
Click Yes when prompted to delete the file and then close Windows Explorer
From the previously opened Command Prompt window type net start ehrecvr and press Enter on your keyboard
Close the Command Prompt window and start Windows Media Center
Note: After deleting mcepg2-0.db, the guide will need to be downloaded and reconfigured by Media Center. Previously configured hot keys may need to be reconfigured. To initiate the download start Windows Media Center and go to Tasks, Settings, General,Automatic Download Options and click Download Now
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