I was out for a few hours last night, and left computer running. When I arrived home, had a screen showing a reboot had happened and no boot record found, screen was half full of 99's.

Checked bios, and my master hard drive was registered as none, slave hard drive showed the paramaters of my master hard drive instead of the one that was actually connected there. Did auto detect on both master and slave and it found both hard drives and put them on the correct master/slave configuration. Booted fine after that.

Anybody able to shed some light on what is going on there?

Do you have your PC connected to a UPS? I'd suspect a power outage or -- more likely -- a spike, but a UPS should have isolated your system from both type of events.

Is you PC old enough that you need to replace the eprom battery?

No ups. Do have surge protected power bars. Normally a power outage causes shutdown, not reboot on this machine.

Use an ECS K7s 5a pro board, about 2.5 yrs old. Clock does not lose time, I thought that would be first sign of battery going dead.

Nah. In my experiance, the first sign is usually losing BIOS settings after a shutdown. You might check your BIOS and/or your Linux settings to see if "reboot after abnormal shutdown" (however it's phrased in your system) is selected. If your BIOS has such a setting, it might have been scrambled at the same time as your drive settings.

Of course, all of the above is only specuation, but it does sound -- to me -- like a hardware problem, which is hard to solve from a distance.

I appreciate the offer, let me know what time to expect you, (realizing it is a long drive), and I shall have the coffee on.
Kidding.

I shall replace the battery this week, as that is a cheap enough trial. This was the first funky thing this pc has ever done. Thanks for the input.

I had changed battery, although when measured, that battery was putting out about 3.27Volts still, so should have been good. All seemed fine till a couple days ago, got nailed by the spysherrif on Windows partition. Decided to leave linux intact and reinstall windows xp today. Xp disk was good, cd rom good, live linux disks booted, 98se booted, XP would not get past "checking hardware". Started this adventure at 8am, finished at about 8pm. During that time I tried probably more things than you can think of including coming up with a host of Microsoft conspiracy theories which I won't get into (due to the coincidental fact that my laptop won't power up as of today as well). Last thing I expected was my newest drive had problems. Only about a year old. So if I don't post back on this thread, these weird symptoms must be due to a bad hard drive.