OK, I'm following the directions for Memtest86. I seem to be having floppy problems--memtest fails when trying to write to the boot disk. The instructions say that I can put the boot image in a directory and point to it from LILO. Unfortunately, I'm not running LILO, and it has no instructions for doing this from grub. I'm reading the grub manual, but it's not clear what commands I need to run to tell it to boot from the image. I tried > kernel /root/memtest/memtest.bin, and I get the message "Error 12: Invalid device requested.

Any suggestions?

[Update about 2 PM EDT]

Thanks for all the help. I found the rpm of memtest86 (they made one for FC-3--who knew?) and installed it (by the way, my problems with downloading files via Firefox seemed to disappear when I logged into X as root). I ran it and it found memory errors immediately. I pulled the stick, and remounted it, and it still has problems. I guess I need new memory before I do anything else with the machine.

[Evening update]

Bought a new stick of DDR 2700, Initial testing shows no problems, so it was definitely bad memory. My next question, per Pete Zaitcev's advice:

What I would do in your place would be to upgrade with yum. It's as simple as one-two:

one: point /etc/yum.conf to FC4, update distro

two: FC4 moves to /etc/yum.repos.d, edit its contents to point to FC5, update distro.

How does one "point to" a distro? Here's my yum.conf now:
###########################
[main]
cachedir=/var/cache/yum
debuglevel=2
logfile=/var/log/yum.log
pkgpolicy=newest
distroverpkg=redhat-release
tolerant=1
exactarch=1
retries=20
obsoletes=1
gpgcheck=1

# PUT YOUR REPOS HERE OR IN separate files named file.repo
# in /etc/yum.repos.d
###########################

So what am I supposed to do to upgrade from FC 3 to FC 4 and then to FC 5?

I'd do a couple of things at this point:

Find an RPM of memtest86 (the search engine which shall not be named helps here), install it (rpm -Uvh memtest-*), then run memtest-setup and reboot. You should now see an entry for memtest86 in the boot menu.

If that doesn't go smoothly, I'd assume that it's due to a hardware problem, most likely bad memory. I'd pull all but a single stick of memory, and swap sticks until I found which worked and which displayed the flakeyness that you're seeing.

Best of luck.

Well, I only have a single stick (512M) of memory...

I'll have to scrounge around to see if I have another that's compatible with the mobo.

You ask "So what am I supposed to do to upgrade from FC 3 to FC 4 and then to FC 5?"

The basic idea is to find an RPM of the version of yum that comes with the version of Fedora that you want to upgrade to, and use the rpm command to install it. In addition to updating yum itself, this will update the yum configuration files so that yum now "points to" the repository for the newer Fedora release.

Ideally, you should be able to just say "yum upgrade", and let the magic happen, but in practice you're doing something that's not supported, and will likely require some manual intervention.

If I were in your position, I'd feel more comfortable backing up /home and any other valuable data, and proceed to download, burn, and install from CDs as you had originally planned.

If you do decide to brave the dual upgrade process, please share your experiences. I'd be curious about how it goes for you.

Rand, sorry for the delay with the answer. Please have a look at this document:
http://fedoraproject.org/wiki/YumUpgradeFaq

The "live upgrades" language means "upgrading a running [production] system", so please do not be deterred by the first paragraph.

-- Pete