"I don't know what is the matter" vs "... what the matter is"

"I don't know what is the matter" vs "... what the matter is"
http://groups.google.com/group/alt.usage.english/browse_thread/thread/8cb0cca7e2590cca/

http://forum.wordreference.com/showthread.php?t=821167

http://forum.wordreference.com/showthread.php?t=81250

http://www.usingenglish.com/forum/ask-teacher/151060-i-know-what-matter.html

http://www.englishdaily626.com/c-mistakes.php?033