A big thanks to everyone for helping with my problems over the last 24 hours. I genuinely thought that the machine was a lost cause. You folks gave me the confidance to get the case open and get stuck in. All fixed (for the moment). I'll be sure and let you know when it's gone wrong again, Thanks.
Sorry woodchip, I closed the other threads with an explanation. You as a major contributor to the outcome are welcome to see it here.
Thank you to everybody who took the time to offer their advice. The solution is perhaps as diificult to pin down as the original problem. By disconnecting the drive completly I was able to re-boot in normal mode, then I went into the registry (for the first time ever) and removed all traces of the CD rom drive. At this stage I was following a step-by-step guide from a Samsung troubleshooting FAQ. I can't post a link because I arrived at the site via about 8 links. Then I Activated a couple of .exe files from the web (another 6-7 links), one was firmware (which I didn't know existed) and the other was a driver. The driver was for a drive with a very similar, though not exactly the same, designation to my Samsung drive. Next I re-connected the rogue drive and re-booted with the Win98 disc inside. I think at this stage I got a choice of starting from HDD or CD-rom, and suddenly there was a glorious sound I've not heard for a while... the Cd drive spun into life!!! I continued with a full installation of 98, accepting I was going to lose everything else, but, when it was complete, all my old stuff is still on there!?!? Anyway I don't pretend to fully understand what was wrong or how i, sorry, we, fixed it, but a great big thanks again to all on the board.
This thread is now locked and can not be replied to.