Can someone help ? Got problem with my computer?

When i reinstall windows 1-2 weeks its ok but then starts to restart all the time and getting some errors like : " Windows could not start becouse the following file is missing or corrupt : isapnp.sys or sometimes file : Ntfs.sys , also sometimes get only blue screen , or disc checking C: or D: and cant turn it on for a day sometimes so can someone help me please i dont know what to do and i dont know is it harware or software in question here for these problem :S ?? Please HELP !?!