Computer Starts with No Files.

Hello,
I have an hp laptop pavillion de 5000, I got in in August of 2006 and no problems. Then around April or May of 2007. When I would turn on my computer there were no files. So then I would manually turn it off and turn it back on and all the files were back. And I learned to live with it. But as of October 2008. It still does it, but now it take 3 or 4 times to get all the files back. And no it is not a virus. I did 2 virus scans and nothing. So i'm not gonna believe anyone if they say I have a virus and to get this anti-virus that really is a virus. I really don't want to buy another one. I saved all my files on disks. So if it crashes it's not a problem. But i really don't wanna get another one. Please write back ASAP. Thank you.