I have WMP11 on my PC and encountered problem while trying to install WMP10 from the installation CD.
Please follow the instructions below to uninstall Windows Media Player 11 before installing Windows Media Player 10
Disconnect the device from PC.
Make sure that WMP11 is not running. If WMP11 window is open, please close the same before starting this process. Sometimes, it is possible that WMP11 is running in the background. To make sure that it is closed completely follow:
Press Ctrl+Alt+Delete to get Windows Security window and select Task Manager button.
Go to Processes tab and select wmplayer.exe process and press End Process.
Open Windows Explorer. Select Control Panel from the left pane. Select and open Add or remove Programs as shown in figure below:
In Add or Remove Programs panel please check Show Updates as shown in the figure below:
Select the following components as per the order and click to Change/Remove to uninstall the same from the PC:
Windows Media Player 11
WMP11 Media format runtime11
Microsoft User mode Driver framework feature pack 1.0.0 (Pre release 5348)
The system will ask you to re-start. Please follow the same and let the PC re-start.
Warning: System re-start has to be done for the changes to reflect properly.
Make sure that all the above three components are uninstalled successfully.
Now you may try again to install the Windows Media Player 10 from the installation CD.