Unrecognized file versions

[matthewk]

Files that are required for windows to run properly have been replaced by unrecognized versions. To maintain system stability, windows must restore the original versions of these files.

Insert your windows xp professional service pack 2 cd now.

I hit cancel, and then I can choose that I am sure I want to keep unrecognized file versions.

I get this when I try to install windows media player 11 msi by Shark. It installs fine if I do the above, but how do I avoid having to do that when I replace important files or whatever is happening?

Thanks