[syslinux] extlinux "boot failed" on older (pentium 3) motherboards

[Nick]

I have 3 older pentium-3 systems (asus cubx, asus cusl2-c) that give a
"boot failed" message when trying to boot with extlinux on a flash card
(which uses an ide converter, so it looks like a regular ide hard drive to
the os & bios).  These worked fine when I used syslinux & fat16.

If I take out the flash card & ide converter and put it in a newer p4
system, it boots fine.  So I would assume that I did the extlinux install
& partitioning just fine.  In fact I have been using it for a while now
with no problems in newer systems, and only now am running into a problem
when I am trying to upgrade some older systems.

I was thinking extlinux would boot on any system that syslinux would.  Am
I incorrect?  Any ideas?