iBook won't recognize keyboard commands at startup.

[The Weber's]

Hello all,

I'm working on 20 iBooks (Rev. C Graphite,
466Mhz/128MB/10GB/DVD/Airport) for the High School that I Graduated
From.  They were pretty messed up buy the students so I'm in the process
formatting all of them and putting a nice fresh copy of Mac OS 9.2.2 on
them (Multiple Users enabled so the can mess them up again ;)).  Anyway,
the first thing that I have been doing to all of them when I turn them
on for the first time is to reset the PRAM.  Here's the problem, on
about 5 of them now, I go to reset the PRAM (power on, hold down
Command-Option-P-R before any thing comes up on the screen) and it just
boots like I didn't hold anything down.  Holding down just option to get
a list of Bootable devices doesn't work, nor does holding down the C key
to boot from a CD.  Any ideas why these few stubborn iBooks aren't
accepting my Key-Combinations?  ClrlCommand-Reset Button does work
though :S

Any advice is more than welcome.

T. J.

PS ~ all the keys in question work fine when the computers are booted