Anyone know what's going on with my netbook?

This is the second time this has happened with my Toshiba Mini Netbook. When I restart it, it will shut down but then not come back up. It seems like it’s running but the screen is blank and the power button is lit. The first time it happened I shut it down via the power button, then turned it back on while pressing F2 and it came up properly. Now, however, it is not doing it. The screen remains blank.

What could be causing this and how do I fix it? It is running Windows XP.