Hive: HKEY_LOCAL_MACHINE
Key: SOFTWARE\Policies\Microsoft\WindowsMediaPlayer
Name: DisableAutoUpdate
Type: REG_DWORD
Value: 1
The same
registry hack works for Windows Media Player 7.0 and 7.1 used in NT and Windows
2000.
For older Windows with Windows Media Player 6.4, the key is HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MediaPlayer\EnableAutoUpgrade, Type=REG_SZ, and value="No".