Beige G3 startup problem

[livingfortoday]

I have an older beige G3 which I finally put back together and have been trying to use as a folding computer and maybe later a slow file server, but it keeps having this really weird problem. Whenever I shut it down and boot back up, it'll flash the disk with question mark, and can't find the boot disk, it seems. I can boot up from the OS X CD (I'm running Jaguar on it), and it sees the hard drive, but when I reboot, it won't boot to the hard drive. I have to reinstall OS X in order for it to boot into the system.

When I restart and hold down "Option" like the CD says to (in order to quit installer and boot from main disk) it doesn't boot up, though I can hear the hard drive spin up.

I have the hard drive and the CD-ROM on their own IDE cables, both set as master. It's a 300Mhz G3.

Anyone know why this is happening?

 

[livingfortoday]

Okay, I reinstalled the system, and this time I didn't run Software Update, and it shut down and booted fine. Last time I had run all the updates and hit "restart", and it had worked, until I shut it down. So. I don't know if there's an incompatibility that's being introduced in an update, or what - still hoping to hear from someone else that may have had a similar problem?