Laptop bahaving badly, help anyone?

[lazygirl]

hey everyone, i need a little help with my laptop as i really dont know anything about pc's. when i start up my computer it works fine for about 5 minutes then the sceen goes blank and i cant see anything, but still can hear the pc working, and doing its thing, i dont know what to do, one of my friends suggested its a virus, but no idea!!! please let me know if u came across anything like this before, or know the solution

thanks a lot

lazy x