PANIC: can't juggle and compress too

Freebsd 4.9
Postgres 7.4Beta5

We have a daemon that among other things vacuums the channels table
every 5 minutes. Worked fine until last night.

Oct 28 01:04:49 ...  postgres[7572]: [52226-1] LOG: statement: VACUUM ANALYZE channels
Oct 28 01:04:50 ...  postgres[7572]: [52227-1] PANIC: can't juggle and compress too
Oct 28 01:04:50 ...  postgres[7572]: [52227-2] STATEMENT: VACUUM ANALYZE channels
Oct 28 01:04:50 ...  postgres[7565]: [1-1] LOG:  server process (PID 7572) was terminated by signal 6
Oct 28 01:04:50 ...  postgres[7565]: [2-1] LOG: terminating any other active server processes
Oct 28 01:04:50 ...  postgres[7630]: [7841-1] WARNING: terminating connection because of crash of another server
process
Oct 28 01:04:50 ...  postgres[7630]: [7841-2] DETAIL: The postmaster has commanded this server process to roll back the
currenttransaction and exit, because ano ther server 
Oct 28 01:04:50 ...  postgres[7576]: [47833-1] WARNING: terminating connection because of crash of another server
process
Oct 28 01:04:50 ...  postgres[7630]: [7841-3]  process exited abnormally and possibly corrupted shared memory.
Oct 28 01:04:50 ...  postgres[7577]: [6-1] WARNING: terminating connection because of crash of another server process
...

I googled  can't juggle and compress too and the only link is to the
actual source.

Bug?

Regards,

Dror

--
Dror Matalon
Zapatec Inc
1700 MLK Way
Berkeley, CA 94709
http://www.zapatec.com