My computer keeps crashing?

[Hannah]

Okay, so my computer keeps crashing every ten minutes or so and I can't figure out why. I don't get an error message, I've don tons of maintenance (Disk defrag, Disc cleanup, uninstalling everything useless, deleting useless files). It isn't getting hot, as I keep one of those laptop cooling fan things under it. I'm afraid to take it apart since it's under warranty. It is a Dell Laptop purchased less than a year ago with all original parts except the hard drive (I dropped it and took it to the geek squad and the only issue was a broken hard drive which they replaced...I have never had prior issues with it.) My version of Windows 7 is also not genuine if that could possibly be part of it?