Are you using either Windows Media Player 10 or 11? The m200 series is designed to operate with WMP10. WMP 11 may work, but I found that WMP 10 does best. Either WMP 10 or 11 must be installed for the m200 to be recognized in MTP format. If you have WMP 11 installed and it doesn’t recognize the m200 in MTP, see the Microsoft info at:
Device not recognized after installing Windows Media Player 11
Some devices that support the Media Transfer Protocol (MTP) might not be recognized in Windows Media Player 11 for Windows XP.
If you encounter this issue, perform the following procedure.
Uninstall the device in Device Manager by performing the steps in Issues with devices after removing Windows Media Player.
Disconnect the portable device from your computer.
Reconnect the device to your computer.
Start Windows Media Player 11 for Windows XP and verify that your device is recognized and displays in the Player.
If this doesn’t get it, try using a different USB port. I have a Dell that locks up if I plug into a front USB port and will not power on if my m250 is plugged into the 4 port hub.