Jof - I appreciate your time analysing this - I think that is the key actually, BUT some more 'odd' events today!
Starting at the beginning, CMOS battery replaced due to repeated 'BIOS Default' events on boot up and repeated 'confusion' over the hard disk boot priority.
Then (probably due to your explanation, although the Windows disk allocation had not changed) I got the boot ini problem, sorted by changing to rdisk(3) as above.
THIS MORNING -what do I get? Default BIOS again
. So I reset to 'normal' and 'hal.dll' missing/corrupt. (Fits your theory)
Win XP recovery in and once again, bizarrely, all it 'finds' is my W2000 installation so I rebuild boot ini with that.
On inspection I find NOW the system thinks W2000 is back on rdisk(1), so I change XP to same and all ok again.
Several questions now:
1) I had actually come across Daniel's article during the initial 'outage' but it did not explain how rdisk and Win disk allocation could differ.
2) Any ideas what can be causing the BIOS 'defaulting' now with a new batt?
3) During 'recovery', bootconfig /list found NO boot entries????
4) Would using bootcfg /redirect useBiosSettings have sorted out the initial disparity between rdisk and Windoes disk numbering?
5) Why did recovery not find the XP installation?