Computer Starts On Its Own.

Sometimes My Computer Will Just Turn On By Itself And Start Windows After It Has Been Shutdown For Hours At A Time.
How Can I Fix This?
Wallace

 

Is the computer on a network? It's possible that a wake-on-LAN signal is being sent. Has the machine actually been shutdown, or is there a possibility that it is entering a sleep mode that it then comes out of later?

Also, sentence case is much easier to read than Title Case.

 

No, there is no network it is just my home desktop. I just replaced the motherboard, cpu, and loaded a new operating system(windows xp). So this just happens after I have logged off windows and clicked on the turn off computer. The light on the computer goes off and everything just like it always did before I replaced everything. Also, can you recommend some good virus protection. I think that is what caused me to have to replace everything.

Thanks
Wallace

 

That's an interesting problem. Is there any sort of regularity to the machine powering up (a certain delay after shutdown, a particular time of day, a relationship to an external event?)

What symptoms necessitated a mobo/proc swapout? A BIOS flashing virus would be a nasty thing to catch (not very effective, though, as it could only target a particular model board), and I don't think that microcode flashing vulnerabilities have existed for some time.