BleepingComputer.com: Driver Updates Say I Don't Have Vista

Dell Dementia 2400
Graphics card NVIDIA 6200
Memory 1.25 GB
DVD drive installed (sorta cheap)

Ongoing issues with cryptic messages, desktop programs disappear, cannot access command line, driver updates inform that I don't have vista as os. All scans show nothing, malewarebytes nothing, threatfire nothing, panda never anything but can't access unless I've reformatted. I don't run these at the same time, I've tried one security sys. or another to no avail. Won't let me download spybot, I'VE HAD IT, reformatted 4 times, changed SID 4 times, upgraded to vista, reinstalled twice. My wife has cancer and I need to be able to trust this machine it would make things a little easier

How did you change the SID?
Does the OS work once you reformat? If so, when does it start not working?

I changed the SID using sysinternals Newsid program out of my sysinternals suite. There are several programs in the suite that utilize command line. when I open one of them and click run they disapear never to be seen again. After a reformat I'll begin to have problems within an hour or so. I tried to reinstall XP so Vista would have a clean copy, part way through it can no longer read the disc and tells me I don't have an os installed, Vista is still there and partly works, I tried to reinstall Vista, towards the end of installation a comand line screen appeared showing a series of musical notes and then it was gone, is some one trying to tell me I'm whistling in the wind? I have Zonealarm on disc, when I install it, it shows a new connection either a network or a computer that I can't remove. Has some one found a port and gotten in, or is my harddrive damaged and leaking info. back out or a combination there of? My cursor dances across the screen by itself, that and the fact that I discovered chunks of memory being consumed points to a virus of some sort, but nothing turns up, I intended to upgrade the harddrive at some point, just not yet. Any and all suggestions will be taken seriously, I thank you for your time.

Something is definitely borked on the system. I'd suggest first trying Darik's Boot and Nuke (free here: http://dban.sourceforge.net/ ) to completely wipe the hard drive out (to include the recovery partition). Then try reinstalling Windows (leave the SysInternals tools out of the mix for now) by using the Dell Recovery Disks.

This will fix any software problems that you may have. Should this be a hardware problem, the issues will continue - then it's a matter of troubleshooting the hardware until the problem component is located.