Hp laptop starts up, but I get a white screen

Hello,
I have had my hp laptop for about two years now and had a few problems. Usually they work themselves out and I end up not having to do anything. Then today, I started up my computer, I get all the mandatory screens, like the windows vista logo, etc and then just before it hits my desktop I get a white blank screen with my pointer in the middle. Every time it happens I just restart and the same thing happens. So I went on Safe mode with networking and I can get on. I haven't a clue what is going on. If you need anymore details or could help me solve the problem that would be great. Thanks.