My two-year old HP desktop running Vista with 3gb RAM has worked well until recently, when this sometimes happens: When I boot up the cold computer, the blue screen of death (BSOD) appears with the message "BAD_POOL_HEADER" followed by something about using the safe mode to remove or change components, and the following technical info: "STOP: 0X00000019 (0X00000022, 0X00000000, 0X00000000, 0X00000000)." I has happened only twice in the past 15-20 boot-ups, and it happens only at boot-up, i.e., it does not happen once Vista has started. When it does happen, Vista never gets a chance to start before the BSOD appears. The two times it's happened, when I shut down right away and reboot, it happens again; however, if I wait five or ten minutes and then reboot, Vista starts normally and all is A-OK. It doesn't appear to be a temperature issue since it only happens at (cold) boot-up. What's going on?