More Vista woes, Baking things into the OS!

Recently, I’ve been having a lot of problems with Windows Media Player 11. It plays a few .wmv files, but cannot play most of them. .avi files play fine always with the divx codec, but I’m at sixes and sevens trying to find the problem with .wmv files. I can, for instance, stream a video from Channel 9, but if I download it, all I get is sound and weird colours on screen.

I have tried to no avail. On one site I could view files that were encoded in WP7 but not WMP 9. I have tried to find the codecs for this again to no avail.

Looking through my Windows updates, no WMP 11 specific updates are available, so I can roll back to the previous version. Why is this? I cannot use system restore because I have installed a lot of programs, and in truth I don’t know when this problem started. All I know is that I could watch .wmv files now most don’t play the picture. I have gone inst cmd.exe and run ‘sfc / scannow’ and that reported no problems.

What would have saved me a great deal of time (days) and frustration was the ability to re-install the application but this appears impossible? Under what justification was this decision made? If a program stops working for me a two minute reinstall is usually sufficient. Is Windows Media Player 11 flawless as to not warrant reinstallation? I cannot believe that even a repair utility is unavailable. I suspect that the problems occurred after the Vista SP1 install but cannot be certain. I am now wasting valuable time trying to locate a fix for this and am severely out of temper.
Any ideas?