What is your system configuration and was it a upgrade or New Pc?
if you can fill me on this one maybe i can help you out i have had serveral problems like this in the past also.
Recently I notice that when I reboot my system with Vista Ultimate, during the CMOS part of the boot process, the screen after the "CD" boot option, the next screen asks me whether I want to boot to Windows Vista. (Vista is the only option so there should be no dual boot operation here.)
I haven't yet waited to see if it would proceed past this screen automatically if I did nothing. Hitting the enter key then boots the system up normally except that it seems to take a long time before the next screen pops up (the colored logo in the center of the screen.)
I've been running Vista on my computer since April with no problems. While I normally run 24/7, I occasionally either shut down or reboot the computer. In the early days of this Vista system (April-May), I don't remember seeing this screen during the boot process.
So, is this normal or an early indication of a coming problem?

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