Yeah, I think you're right, Richard.
Funny, though, I have two machines (laptop and desktop), networked, both P4, 512MB Ram, heaps of disk space, XP Home SP1 fully updated.
Both systems reinstalled in July after crashes - I stuffed the laptop through ignorance, now much wiser. Can't believe how stupid I was!!!. The HDD in the desktop died with a physical failure within 36 hours of the laptop failure. You wouldn't read about it! Point is, neither installation is very old.
And they both have this same ntdll.dll problem. There has to be a link there, but I can't pin it down.
So I'm backing up each to a partition on the other and will do as you suggest, one machine at a time.
I've been letting these machines report their problems to MS. I bet that soon after I've been through these two OS repairs/rebuilds, chance will dictate that a fix will appear in the MS knowledge base.
Who asked if I'm paranoid, and why do they want to know!
Cheers
AA