Depressed XP Pro Owner

6 months after buying a lap top from a personal add, Microsoft has informed me that the VLK licence has been block for use. I perchased another OEM cd with code, when I try to install it the blue screen tells me computer has been stopped, sometimes it says I may have a virus ( I don’t,it has been scanned and updated) or it tells me there is no hard drive detected ???what??? I don’t want to format HHD and would like to keep updated programs and files from the existing OS. Is there anything I can do myself?