nvcpl.dll error

My son deleted nvidia from add and remove products for some reason, I've been having a problem since then like: when i scroll on files it gets laggy and instead of scrolling it jumps, it also gets a pop-up when the computer starts...

after the error is shown the computer goes extremely slow for the first 40-50 seconds, i tried to download that file off of the microsoft website but it showed a different error stating something about routing to the file i inserted the system disk and ran sfc /scannow and at the end of checking it ended, after that i restarted but it was exactly the same. i looked at the dell help and support but it didn't help. i tried a system restore, but the only restore point was after the problem already occurred.

i have:

inspiron 5150 (laptop) windows XP

 

 

if anyone has any idea how to solve this problem please post, or if your having a similar problem tell me what happened so i can see what triggered it.