Under normal circumstance this doesn’t happen. Though we cannot say for sure what could possibly be invoking this behavior, try these few suggestions that should help in narrowing down the root cause.
1. Have you installed any third party Codec?
Windows 7 has inbuilt DVD codec hence making it unnecessary to install other third party codecs. If you’ve installed any, please remove all of them. For test purpose, please remove all the third party burning software. You may choose to install them later
if it doesn't conflict with Windows media player.
2. Change Hardware Acceleration. This will verify if you’ve the correct display driver.
1. Right click the Windows desktop and choose Personalize.
2. Click "Display Settings".
3. Click "Advanced Settings”.
4. Click on "Troubleshoot" tab.
5. Click on "Change Settings".
6. On the resulting Display Adapter Troubleshooter dialog box, drag the slider one notch to the left.
After setting the acceleration back, run Windows Media Player (WMP).
Is there any improvement?
You can either reduce the acceleration a notch at a time until the problem goes away, or move it all the way to the left, test, then if that cures it, try moving it to the right again until the problem recurs, then back off one notch.
If changing the hardware acceleration solves the problem, it's a signal that your computer's display driver isn't quite perfect.
To get the correct driver, please visit your Manufacturer’s website and get the proper download for your operating system.
Check your manufacturer details from DirectX Diagnostic Tool:
1. Open the Direct X Diagnostic Tool. To do this, click Start, type dxdiag in the Start Search box, and then click dxdiag.exe in the Programs list.
2. Click the Display tab.
3. Under Device, look for Name and Manufacturer.
4. Click Exit.
Make a note of the manufacturer, visit the website and download the appropriate driver for your graphics card driver that is compatible with Windows 7.