While installing xp its shows some sys file is missing wat to top

[Guest]

initially i used windows xp but later i had installed windows 7 ultimate but i did not like that so i re installed windows service pack 2 but it shows tat some .sys file is corrupted wat to do pls help

 

[aford10]

Use a few drops of water and a soft cloth to clean the disc. It may be scratched or smudged.