O/S Curropt

Hi,

I am using a 7700 HP Desktop, who’s O/S has got curropt, it regulary prompts for McShield.DLL, and some other errors as well, I tried system restore as well, but that too is not working, apart from full system restore, is there any other way, to come over the problem, as there is lot of data on the HDD,

Any Suggestions , pls do let me know you can reach me at javid.amin@hotmail.com