I'd make a new Windows account and see if that's OK. If it is, it's the well-known corrupted account. Move your files over to the new account (I don't think there are many) and delete the old one.
But I wouldn't use Windows XP on a 256kB machine (not even MS-DOS did that). Not even on a 256 MB machine, although that is possible if run no antivirus and hardly any application.
What I would do: add RAM to 1 GB, add a second hard disk and install a Linux variant like Ubuntu or Mint.
THE SYSTEM: XP Home SP2 on Dell Dimension 8100 1.5 gHz 256k, a junkyard pickup last used three years ago. System was an upgrade from ME and came with no disk. 40g HD full of movies.
THE PROBLEM: Hardware reports FD seek failure, otherwise comes up normally to a blank XP desktop -- NO ICONS, NO TASKBAR. No explorer task is running. Using task manager to start explorer gets icons and
taskbar; operation then is normal except occasional freezeup that can be broken only with power button. Running in diagnostic mode (non-essential tasks turned off) is same.
DIAGNOSIS: A virus prevents explorer.exe (which is the WIN shell and displays icons and taskbar) from starting normally but there is a working copy of explorer in the proper place -- c:\windows.
WHAT I'VE DONE: Run malwarebytes, superantispyware, and latest MS malicious software removal tool. Both of the first two found >100 tracking cookies plus a couple of copies of malware called GENERAL something -- didn't write it down. MS MRT (run after) found nothing. Removed all installed programs I didn't need -- games, lots of movie/video stuff, comcast, AOHell, the movies. Ran CCleaner which
deleted another 3.5 gB of stuff (!) and found and fixed 546 registry issues.
Downloaded/ran Kelly's Corner #195 fix for no icons/taskbar: Ran fine but no effect.
Looked in root, WINDOWS, and the two SYSTEM folders for suspicious files with recent dates and obvious bogus copies of explorer; found only a couple of claimed movies in an unfamiliar format in SYSTEM32 and removed same.
WHAT WOULD HELP: 1. Theory/internals info that would help me figure out what to look at/do next. 2. Ideas about what to try.