screen flashes???

hello people...newbie here. i looked thru the search engine for the answer to my quandary but i was not able to nail down a definite answer. I bought a macbook one week ago today. I've found that if i leave it idle for about 10-15 minutes that the screen will start to flash and the fan will come on...i move the cursor and it stops...well the flashing, the fan continues to run. its been doing this since about the 3rd day of having it.

anyone have a any insight to what this is. is it a problem? i also found that one time while starting it i heard a loud signal type beep. caught me of guard and seemed a little out of places considering when i usually start it up i hear the light chimes not this big beep type sound.

thanks in advance

How long have you had your computer? If it is still within 14 days, go exchange it for a new one. This could be something that software up date could fix, or resetting the pram or pmu. But beeping on start up isn't good.

1 beep = no RAM installed
2 beeps = incompatible RAM types
3 beeps = no good banks
4 beeps = no good boot images in the boot ROM (and/or bad sys config block)
5 beeps = processor is not usable

Maybe your ram is going bad? Maybe it's a fluke? Either way, it isn't normal and you should exchange it or have apple care send you a box so it can be looked at.
Mainly, you should call tech support and atleast have them make a case and do some over the phone appeasement's. This way, if you wake up two months from now and your mac is dead, Apple has a trail. It will give you a speedier resolution.
If you are within your 14 days, exchange it. Who needs the hassle of repairs and tech support. If your not, then call tech support. beeping on start up isn't good. No matter what it may be from.