laptop problem

[Wizzy33]

My laptop is a Dell Vostro 1700 and works really nice and fast except i have this one annoying problem. Whenever i leave it and come back like 20 minutes or more later it is unresponsive and wont load any programs or anything. Also ctrl alt delete doesn't load and i basically have been just holding the power down to shut it off. when it reboots though it works like a charm again. This just started 2 days ago....my laptop is 1 month old only

Any help would be greatly appreciated.

Thanks.