WANT INFO ON dELL d5110 TOWER PC

SOURCE: Dell 4700C randomly goes into "sleep mode" and doesn't wake up.

Honestly, my first suggestion would have been to upgrade your memory. If you go into control panel and check your power settings (I'm assuming you're on windows XP) Do you have all of you options set to "Never"? You may also want to check your BIOS settings to see how your sleep/hibernate is set up. Aside from that, you'd have to run some hardware diagnostics to give a better idea of what to look for. Hope this helps!

SOURCE: the motherboard cannot detect the hard drive/ hard disk

You cant install xp on one machine and then move the drive to another. By nature the xp install is tied to the hardware of the machine it is installed on

SOURCE: free virus removal from Dell PC

you can try avast at:
http://www.avast.com/eng/avast_4_home.html

or
malwarebytes at:
http://www.malwarebytes.org/

both softwares are good and free.
the memory of the system will depend on the capacity of the RAM installed on the system. you can either upgrade the memory (RAM) or stop applications from running at start-up

SOURCE: Dell Dimension 4600 Won't Boot Up, Steady Amber Light is on tower

It could very well be the Mobo or the power supply. You may want to try to take the CMOS battery out for a few mins as well, I have had problems with that. But I would try PS first, get one from Circuit city or another electronics store and if it doesnt fix it take it back. I dont know if you know a lot about computers but you could buy a new Mobo just make sure the Ram and Processor match up

SOURCE: Booting Problems With Dell Optiplex gx270 and gx260

Does anything show up on the screen when you access your BIOS?
Have you tried a fresh install?
Are there two video adapters installed (one integrated and the other in the AGP slot?