Loading <imagename> PBS...Bad format or I/O error Press a key to reboot
... then this might help.
Boot from your install floppy. When the system comes up, open a shell window by using the right mouse button against the rio backdrop. At the command prompt, type the mount line that is listed in the "status" window below your install command interpreter window. This will mount your hard disk at /n/kfs.
Now, do the following:
term% cd /n/kfs/386 term% /n/kfs/rc/bin/9fat: term% cp /n/9fat/plan9.ini . term% unmount /n/9fat term% disk/format -b ./pbslba -d -r 2 /dev/$DISK/9fat ./9load ./9pcdisk ./plan9.ini
... where $DISK is your system media; mine is sdC0. The mount command you gave before should give you a clue.
Reboot.