pls help me to solve this problem

Hello friends , when ever i on the system i get this msg , pls help me
out what i have to do. I dont have WINDOWS XP CD ... Pls help me.

files that are required for windows to run properly have been replaced
by unrecognised versions.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

Insert your Windows XP Professional service pack 2 CD now.


More information
You have inserted the wrong CD, (i.e , a different windows product CD
than the version installed)
The CD-ROM drive in your system is not functioning.