psql died in midst of session

This has not happened before to me. I'm running postgres-9.0.4 on
Slackware-13.1. I've been working on the command line using the psql shell
updating and fixing a table when the application failed on me:

PANIC: could not open file "pg_xlog/000000010000000000000046" (log file 0,
segment 70): Permission denied
PANIC: could not open file "pg_xlog/000000010000000000000046" (log file 0,
segment 70): Permission denied
The connection to the server was lost. Attempting reset: Failed.
!>
!> q
->
->
!> Terminated

When I try to restart postgres (as user postgres) I get this:

postgres(at)salmo:~$ postgres -D /usr/local/pgsql/data &
[1] 17783
postgres(at)salmo:~$ LOG: database system was interrupted while in recovery at
2011-10-12 13:00:05 PDT
LOG: database system was not properly shut down; automatic recovery in
progress
LOG: consistent recovery state reached at 0/4581E51C
LOG: redo starts at 0/457EC9C4
PANIC: could not open file "pg_xlog/000000010000000000000046" (log file 0,
segment 70): Permission denied
LOG: startup process (PID 17784) was terminated by signal 6: Aborted
LOG: aborting startup due to startup process failure

[1]+ Exit 1 postgres -D /usr/local/pgsql/data

pg_xlog is owned by postgres.users and has permissions 755. The /tmp/.S
file is not present, either.

Please advise me how to recover from whatever happened so I can get
postgres up and running again.

Thanks,

Rich