My HP - Mini Netbook / Intel® Atom™ Processor / 10.1" Display / 1GB Memory / 160GB Hard Drive won't start up?

When I turn it on, a black screen pops up, with only one small blinking light in the top left-hand corner of the screen. I had this problem last week and had it fixed. I used it today and it was working just fine, I was on the internet and it just shut off on me. The the same black screen poped up. Could some one please tell me what the issue is and how to fix it, and (if possible) how to prevent it?