My Pc Freezes after 10mins or so after booting. Once or twice it has shown a blues screen error message System-service-exception 0x0000003b other times just a black screen and PC does nothing , have to switch of at mains or power off ( is this harmful? ) I have run mailbytes nothing thrown up! deleted duplicated devices in "device manager" fragmented, basically all the things I know how to do.! Is there a fix for this problem or should I get it looked at professionally !! Any help advice appreciated.