HELP: Oracle instance down, and it can't get up. Root cannot even help.

I've been running the same instance of 8.1.5.0.1 for a while now, doing some research on optimization issues. During a longish run (3 days) it crashed, and I can't get anything to work.

It's 8i under RedHat Linux 6.1. The SID is TPCX.

The final alert_TPCX.log ended with
  PMON: terminating instance due to error 601   Instance terminated by PMON, pid=847
BTW I had never looked at this log before. It had thousands of entries, going back a month, at intervals of about 1 minute, saying   Load Indicator not supported by OS !
and I have not a clue what that means.

The final line of pmon_847.trc is
  DUMP FILE SIZE IS LIMITED TO 5120000 BYTES but I cannot tell if that has anything to do with the error, because the line before is a two-day-old timestamp, and the failure is timestamped just ten minutes before I noticed the processing had stopped, and that was today.

None of the other logs seem to have anything interesting to say.

The problem is now most confusing: I cannot run any of the Oracle binaries, even as root. I didn't know this was even possible. Here's a snippet of what happens when I try (note that I su to oracle, then su to root):

Script started on Sat Jan 29 14:05:12 2000
[kevin_at_glynnis kevin]$ su oracle

Password:
[oracle_at_glynnis kevin]$ cd /sql
[oracle_at_glynnis /sql]$ sqlplus /

bash: /u01/app/oracle/product/8.1.5/bin/sqlplus: Permission denied
[oracle_at_glynnis /sql]$ su

Password:
[root_at_glynnis sql]# sqlplus /

bash: /u01/app/oracle/product/8.1.5/bin/sqlplus: Permission denied
[root_at_glynnis sql]# cd /etc/rc.d/init.d
[root_at_glynnis init.d]# ./dbora start
[root_at_glynnis init.d]# -bash: /u01/app/oracle/product/8.1.5/bin/dbstart:
Permission denied
./dbora stop
[root_at_glynnis init.d]# -bash: /u01/app/oracle/product/8.1.5/bin/dbshut:
Permission denied
exit
[oracle_at_glynnis /sql]$ exit

exit
[kevin_at_glynnis kevin]$ exit

Script done on Sat Jan 29 14:06:16 2000

All these binaries are owned by oracle.dba, and I cannot imagine why I'm getting this
error, especially as root. File permissions are typically 751 or 755.

Help, anyone, please!

-- 
Kevin O'Gorman  (805) 650-6274  kogorman_at_pacbell.net
Permanent e-mail forwarder:  Kevin.O'Gorman.64_at_Alum.Dartmouth.org
At school: kogorman_at_cs.ucsb.edu
Web: http://www.cs.ucsb.edu/~kogorman http://trixie.kosman.via.ayuda.com/~kevin