Backend cache invalidation initialization failed... HUH?

Here's the problem:

[rschutt(at)jin logs]$psql transfer
NOTICE: SIAssignBackendId: discarding tag 2147482551
Connection to database 'transfer' failed.
FATAL 1: Backend cache invalidation initialization failed

The frustrating thing is, psql seems to go thru phases where it will work
fine for a few minutes, and then it won't work at all for a few minutes,
then it will connect about 5% of the time for a while, and then it will
connect about 50% of the time.

Here's my config:
sparc SunOS 5.5.1, postgresql 6.3.2, apache 1.2.6 with mod_jserv, mod_php3,
and mod_perl compiled in (persistant mod_perl connections via Apache::DBI),
perl scripts accessing postgresql thru DBI, java servlets accessing
postgresql thru jdbc, and a few php pages.

It seems that all applications seem to connect or fail to connect to
postgresql with the same success rate.

Restarting apache seems to clear up the problem..

Any help would be greatly appreciated!!!