If you continue to have problems, one solution would be to backup anything important and re-install windows on your machine. Windows often kills its self after a few months of use, though some people put up with a crippled operating system for years until it won't boot anymore. Then they send it too some shop that charges them an insane amount to re-install windows. Be wary of PC repair shops, they will try to sell you everything they can most of the time, some don't, but they are few and far between.