I'd suspect the following:
1) Underfootware packet-writing drivers
Packet writing is a way of treating xxRW disks as "big floppies", so
that you can simply treat them as such from Windows Explorer or any
other Windows application.
Behind the scenes will be a 3rd-party service that may lurk in the
SysTray; either DirectCD from the Adaptec/Roxio camp, or InCD from the
Nero camp, or sometimes something else. If you have more than one of
these running at the same time, mileage is likely to be adverse++
Packet writing generally sucks, because different tribes can't always
read each others' disks, and because of the "lazy write" problem that
typically leaves you with a disk that has no files and no free space.
Usually, "lazy writes" are used to speed up slow storage devices;
writes are held in memory and written to the device "later".
Bad-exit, crash, or remove the storage device before this happens, and
you end up with a data barf.
But there's another reason to resort to "lazy writes" that applies to
xxRW disks and USB flash drives (but not SD cards) alike; a limited
write-life for the storage technology. In this situation, delayed
writes may be even "lazier", so that multiple write operations can be
combined and thus extend the life of the storage.
2) MRU and other integration links to optical drive
If you've ever "opened" material off CD/DVD, and especially if you've
inadvertently created a file association to an executable there, then
the system is likely to nag the drive all the time.
One sees this a lot with diskettes too; in Win9x, the PIF folder
(under Windows) is another source of this, as .pif settings for
removable disks are stored not on the disks, but in PIF.
3) Pending XP "CD writing" writes
XP has native CD writing, but it's pretty awful - it mixes the worst
of both packet writing (pending writes) and "normal" CD/DVD authoring
(multisession compatibility issues, treats xxRW as xxR disks).
Material that you may think was written to an optical disk, may be
left lying around in a deeply-nested "CD Burning" folder that's
repeated within each user profile. That can be a lot of gunk bloating
up the C: volume. That material will also show up as "ghosts" on
every data disk you insert in the drive; the idea is that it's
material that would be on the disk if you were to write it there
(which it would do as a new session, not via packet-writing).
You can disable XP's native writing via right-click on the drive
letter, Properties, and UNcheck "enable CD recording". I always do
this; formal authoring via Nero may be a pain, but at least I can see
exactly what's on the disk and how it was written there.
4) Autoplay
Like Win9x, XP will look for an \Autorun.inf on a newly-inserted disk,
and interpret it unless this is suppressed at the drive letter or
device (NoDriveTypeAutoRun) level.
Unlike Win9x, XP will also grope the contents of CDs, DVDs and flash
drives when they are discovered, to "autoplay" them however it deeps
appropriate, based on the types of files it finds there.
5) Bad drive or disk
Because XP has so many background file gropers (indexers,
thumbnailers, etc.) you may find the presence of a disk in a duff
drive, or a duff disk, will slow down the whole system.
This may affect some XP systems and not others, depending on what
native services are running, and especially depending on what
3rd-party underfootware - such as av, camera image transfer
(f)utilities, etc. - are added. The latter can stink up Win9x too.
