Flashing screen at boot up

every time i boot up my pc my screen flashed on and off about 4 to 5 times y is it doing this once its all loaded up it dont do it no more thow please help i have a navida quatro 3700/4400 256 mb video card on a dell dem 4700 with 4 gig ram and a 500 gb hard drive and a 1 gig bigfoot enternet card and i have extra cooling fans in it

First off relax, for the same thing pretty much happens to me when I turn on my computer. Seeing you and I almost have the same machines, mine being a old Dell Dimension 5100c, 4 gig's of RAM, Intel Pentium 4 (H/T) 3.0 CPU, Nvidia Quatro 285 video card.............I think it's just something that happens to systems like yours and mine. For me this flashing on and off a couple times really get's to me, happens on both my dual monitor setup. Sometimes I think I should pop some pop corn and grab a drink and sit back and watch the flashing show!

thanks for the input