Can't dump database

I can't do database dumps! I just get this error message:
getFuncs(): SELECT failed. Explanation from backend: 'ERROR:
getattproperties: no attribute tuple 1255 -2
'.

This is regardless of which database I try to dump (including newly created
totally empty ones), with which user (my "normal" user, any other user or
postgres), or whether or not the database has any functions in it.
If I run pg_dumpall, it starts dumping some stuff from template1, but when
it connects to the first "regular" database, it bails ut with the same
error. Also, just running "pg_dump template1" generates that same error too.

I'm running PostgreSQL 7.0.2 on LinuxPPC-2000. I've also tried the same
thing on LinuxPPC-1999. Same result.

/John