Window media player!!

Microsoft Windows Media Player 11 may be unable to transcode digital rights management (DRM)-protected media to fit on a portable media device.

To work around this limitation, use one of the following methods, as appropriate for your situation.

Method 1: Disable the "Copy protect music" option, and then re-copy the content
1. Right-click the Windows Media Player toolbar, point to Tools, and then click Options.
2. Click the Rip Music tab.
3. Click to clear the Copy protect music check box.
4. Re-copy your music.

Method 2: Disable transcoding
You can disable transcoding for a device if the device supports playback of media files in their original state. To do this, follow these steps: 1. Right-click the Windows Media Player toolbar, point to Tools, and then click Options.
2. Click the Devices tab.
3. Select a device, and then click Properties.
4. Click the Quality tab, and then click to clear the Convert music, pictures, videos, and TV shows as required check box.

Method 3: Disable the "Copy protect music" option, and then burn and re-copy the content
You can burn content to an audio CD and then re-copy that audio CD to non-protected Windows Media Audio files or to non-protected MP3 files. To do this, you must have the rights to burn DRM-protected music to an audio CD. After you burn and copy the media, Windows Media Player can transcode the media for your device.

Note When you burn content to an audio CD and then re-copy the content to a Windows Media Audio file or to an MP3 file, the quality of the audio may be reduced. This reduction in audio quality is especially noticeable when you use a reduced bit rate compared to the bit rate that is used in the original file.

it sometimes happen on me as well, but let say, i will use different programs to run different things, such as video, CD, VCD, DVD or rmvb , etc. i will show what i will use for different formats, but for reference only.

CD music -------- itune
harddisk music ------- windows media player
DVD ------------- mostly windows media player
rmvb ------------- realplayer
avi ----------------------- window media classic

i don't know deep details on why media player will hang while playing CD, but if you can do something about it, just do it. it won't waste you a lot of time to install itune to play CD anyway.