I would suggest you to check for an option in Windows Media Player if it is enabled or disabled. Follow the below mentioned steps and check-
1. Click the Start button, click All Programs, and then click Windows Media Player.
If the Player is currently open and you’re in Now Playing mode, click the Switch to Library button in the upper-right corner of the Player.
2. In the Player Library, click Organize. Click Options.
3. Select the tab Player from the multiple tabs and under the option Player settings uncheck the option “Keep Now Playing on top of other windows“.
If the issue persists disable and then enable Windows Media Player from Windows on or off features option under Media features and check if this resolves the issue.