IMO, looks like a registry corruption problem (Windows problem) and not one that is easy to fix.
From what I have looked at, I would simply do a reinstall of XP to repair XP. That would correct the registry, replace system files, but leave your data and program files as they are. It would require redoing all critical updates since SP2 (approximate total of 100), but that's all WinUpdate activity that is easy as long as one is not on dialup.
I've had this one before and that's how I handled it, rather than trying to troubleshoot something that seems to be poorly/inadequately documented with a known resolution.
But wait for suggestions from others here