Could this be a virus or has my desktop completly turned to the dark side?

Problem I click start- control panel- display and this is where it gets spooky when I click on settings my computer reboots .For some Ungodly reason the thing reboots every time .I have tried every option I know how can some one out there please help , before my desktop meets some terrible fate .ex . a quick slam to the floor!!! Operating system windows XP professional.