If you’re using Windows 7 then most probably you’ll be using Windows Media Player 12. WMP 12 can play DVDs. The problem arises when you want to enable the subtitles in Media Player 12 when playing a DVD. The subtitles begin flickering during movie playback.
Microsoft has confirmed that this is a problem with Windows Media Player 12 and has issued a fix for this issue. The issue also applies to Windows Server 2008 R2. If you want to resolve this issue, you can request the hotfix (KB975806) provided by Microsoft for fixing Windows Media Player 12 Video flickering in Windows 7 and Windows 2008 R2.