I,ve got a 486dx/66 with win98se on quantum hardisk 850mb. The bios is able to autodetect the hd. I also have a 1.44mb A drive and a 1.2mb B drive. The Ontrack Diskmanager V9.52( booted from A drive) is also able to detect the hd, but when I power on or boot from a fresh restart, the message disk i/o error, replace disk and hit any key when ready appears. Any help to get my hd to boot again much appreciated

You could try booting with a Win 98 boot disk, and at the A: prompt, type: fdisk /mbr (enter) Then type sys C: (enter) After it says "system transfered", eject the floppy and hit Ctrl Alt Del to reboot. If you're lucky, it'll come up. If not, your HD may have gone south, which is exactly what just happened to me on a similar dinasaur PC at a clients office.

Try unpluging the unit and move you jumper to clear the cmos , then boot back up for a few mins, then move your jumpers back , I encountered the same problem with my sons ,.. (or remove your battery ,then boot , then reinstall it then reboot)

If you want to clear the CMOS ina system this old, be sure you write down all the needed info in the CMOS first. Secondly, and more important, if you want to clear the CMOS, do not power it up with the jumper set in the clear CMOS position, you could fry your BIOS chip. The BIOS gets all of it's power from the battery, so all that should be done, if you want to clear the CMOS is to either move the jumper to the clear cmos position for several minutes (don't turn it on), or take the battery out for a few minutes and put it back in.

Check into the minimum requirements for running Windows 98 with Microsoft.