Windows XP Pro Sp2 cannot boot: drvmain.sdb corrup

[kapoor 0]

My Windows XP Pro sp2 PC is not booting.

It is giving the message:"C:\WINDOWS\AppPatch\drvmain.sdb"

is corrupted or missing". Safe mode is also giving the same message.I tried recovery cosole.Ran chkdsk C: /R. It completed

successfully.But after exiting from recovery console while booting getting the same error and cannot go beyond that.

I copied the file from from the original installation cd to

C;\WINDOWS\AppPatch directory.While booting it gave the

same error. Please help. Thanks in advance.