Every day I've turned my laptop (Dell Studio XPS) on this week, I've gotten this error on the boot up screen. It follows with "PXE-M0F: Exiting Broadcom PXE R0M. Operating System not found."

Upon turning it off and restarting, it loads up fine, but I don't understand why it's doing this and I don't want it to get worse. 

I've had AVG run system repair and nothing, I ran the pre-boot diagnostics and it said no errors, and I used the My Dell diagnostics tool, and my laptop passed. I was going to do a restore, but it said I had no previous dates to restore to. What can I do?