By the way things looked in the original post; he was not able to bring up the Task Manager and the menu bar. So, unless you want to go through the hassle of creating then booting and scanning from a rescue CD to run Malwarebytes and HijackThis on the troubled partition, its seems like a system wipe might be the simplest solution at this point (baring a successful repair install – see below). Again, do this only if you don't care what is on the original drive.
Also, I meant to ask earlier - when you boot up to an empty screen have you tried hitting CTRL-ESC or the Windows key? You can also try Windows-R to bring up the run window and then type “run explorer.exe” to launch Explorer. If neither of those works, then the Explorer executable is not behaving properly. Once you have the Win2000 system disk, I would also suggest that you try to repair the Windows installation first before a wipe and re-install. The repair may fix the problem you are having with the task bar. Then you can go through the Malwarebytes and HijackThis steps outlined in the sticky ukulele_ninja referred to.
Frankly, depending on the severity of the potential viral or malware infection, a clean wipe is not only the safest, but the least time consuming way to go just to get a system up and running. Make sure that you back up files you want to keep before erasing the hard drive and then re-installing it. To do so you may have to remove the hard drive from the laptop and, with an external case/adapter for the 2.5” hard drive mount it on another computer to pull off the files you want to keep. While you are at it, if you go this route, it wouldn’t hurt to perform a virus scan on this hard drive before pulling any files off. No need to infect another computer.
