I have a new HP Pavillion computer - 6gig ram-AMD quad core. After installing several programs, i.e. itunes, the system will not reboot. I get an error message 0xc000000f. Through the interface that is on the computer I can reinstall windows. It is Vista Home Premium 64 bit. This has happened 3 times. Everytime it happens I loose what little data & formating I have. Can anyone suggest what might be wrong? Thanks in advance.