Windows File Protection alert. How to address / fix?

[smxp]

I have just received a dialog box stating:

"Files that are required for Windows to run properly have been replaced by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

"Insert your Windows XP Professional CD2 now"

I do not have a cd to insert. Is there a way to create or acquire one? Also,
my system is a Media Center Edition 2002 SP2.

Is this alert indicative of other potential problems? What could cause this
WFP alert to occur and is my system's security and performance at risk?

Thank you.

 

[Leonard Grey]

You can also restore the files from your MCE CD. If you don't have an
MCE CD you can restore the files the C:\i386 folder, if you have that
folder. If you do not have that folder, contact your system builder for
help.

If you did not install a program immediately before seeing that message
then your computer is most likely infected.

Windows File Protection is a security feature of Windows XP (and MCE is
just another version of XP) that guards key operating system files
against unauthorized changes.