CDR writing failed, now getting constant disk activity

We have a machine here with numerous OSes installed
for software testing, one of those being Windows XP Home.

I decided to transfer some files to CDR (Philips PCRW804
drive) and dragged and dropped a fair number onto the
CDR icon.

The progress in transferring to the staging area was
relatively slow, and then suddenly the PC turned itself
off.

Now when I boot back into that same version of Windows
XP (no other Windows OS or non-Windows OS is affected)
as soon as I actually log on (and not before), and log
in as any user, I get continual disk activity slowing
the computer down to a crawl. (It can take several
minutes to delete a file, for example).

I suspect that this is a hang over from the attempt
to stage the files for CD writing.

Booting into the other OSes has allowed me to examine
the disk. I've removed all the temp files from
WINDOWS/temp, my user space, and anything else that
looked like it could have been related to the staging
of files. I've even tried turning system restore on and
off (maybe not a wise move with hindsight). Nothing
seems to be working.

What I did notice is that there is a rather large
pagefile.sys (1.5GB) on the disk partition which was
providing the staging area.

Also sometimes I can get the computer to become
responsive again for about a minute at a stretch by
ejecting the CD tray (even though it is empty). This
is not reliable, and is only a temporary fix.

I could reinstall, but I don't want to have to go that
far, and reinstall all the tools, etc., not least because
it has required some delicate balancing to get about 15
operating systems on one PC.

Any hints would be most grateful.