Lost MP4 File Associations

[rwise29210]

OS: XP SP3 I can't run either WMP or Limewire player to play MP4 files.

From CCleaner Registry Cleaner: Unused File Extension .mp4 HKCU\Software\Microsoft\Windows\CurrentVersion\Exp lorer\FileExts\.mp4 (NOT FIXED)
I just left this one alone.

In Explorer I just get the generic file icon with unknown file type.

Any ideas?
Rodney Wise
***EDIT***

[RobertR]

Acording to my research mp4 is a movie file which can be played on the likes of The Quicktime player and other movie players that are compatable with that file type.
Limewire and Windows Media player are both audio players so it's doubtful that one of those two would be sucessful in playing the mp4 file type.