John , first of all; thanks so much for the time you've spent on this, I really do appreciate your help.
I've had no internet for the last 24hrs (for reasons you may be able to guess at...) so sorry it's taken a while to get back to you.
I upgraded this laptop from and 80Gb to a 160Gb hard drive about a year ago and (as I've had problems with hard drives failing in the past) rather than format the old drive and use it - I just kept it. I dug it out today and put it back in to have a look through device manager and the registry to see if I could find out what was going on. Although very sluggish (one of the reasons I opted for a clean install rather than a repair install) everything was once again nicely in order.
First thing I found is that with the old installation there is no phantom drive and the modem card works fine (I had to install it as I hadn't bought it when I got the new drive). So I am sure it's an issue with my new installation of windows rather than any of the hardware.
The second thing is that the ACPI devices that were previously installed have disappeared - my guess is that this phantom drive is actually an ACPI device that's been incorrectly identified by windows (much as you suspected).
I was unable to find anything in the old version of the registry at the PNP0700 address so I'm none the wiser as to which exact bit of the system it is.
I'm willing to bet that if I can get the ACPI devices to appear and install correctly the phantom drive will disappear and I wouldn't be at all surprised if the modem works also.
To that end I put the new much bigger (and even then 3/4 full) drive back into the system and backed up all the data ready to try another re-install of windows.
This is where I realised what was probably the root cause of the problem: After backing up all my stuff I had formatted the hard drive and then did the installation from the XP Pro 'recovery' disk supplied with the computer, but there was a problem; each time I tried to do the install the computer turned itself off without warning a few minutes into the install.
I tried using F5 at the 'Press F6 now to install third party drivers'
to bring up options but there were only two in the list; Standard i486 C-Step
(something like that but I can't remember the exact words) and 'Other'
if I selected 'Other' then the install reported 'Cannot find txtsetup.oem'
and using the 'i486' option still caused the computer to turn off during the install.
F7 to the rescue! (or so I thought) By pressing F7 at the 'Press F6'
prompt the computer sailed through the installation process and has indeed been running much faster and more reliably than it was before (albeit with these few small glitches) F7 turns off ACPI support (I thought just during the DOS part of the setup program) and so I think that it was has caused this whole mess.
And so here I am back rather at square 1.
I have re-installed windows today (a repair install) and eventually got back to the exact same situation - no ACPI, a phantom floppy disk drive and a modem that won't work also this time a mouse that won't work (until I swapped the nice logitech driver that I like for the default windows one) and a couple of other new program errors.
So then I tried a clean install but have hit the same problem, the only way I can get install to run is by hitting F7 to disable ACPI (which I suspect will cause all the same problems to appear all over again) so I've now got a more broken system than before, and although I'm little more knowledgeable as to the cause of the problem - I'm not much nearer to a solution.
Anyway - as this post demonstrates I'm now back online (thanks to one of my neighbours unsecured wi-fi) and will search out a solution to install ACPI with windows XP - as ever any information gratefully received.
One other thought does occur to me - I could copy the disk content from the old drive onto the new one and then try a repair installation over that....
Thanks again to everyone for your help.
I bought the system in the UK but it is now out of warranty
I can't find ant tech specs for it online but the user manual is here
also there a review with some details here.
As you can see this is not a low end machine and I bought it after being very pleased with Samsung X10 I had before it but I have to say their support is disappointing.
Edited by Adam.H, 14 January 2008 - 09:00 AM.