Tests randomly failed

Hi all.

First time I execute `make check' 10 tests failed:
     float8               ... FAILED
test numerology           ... FAILED
     point                ... FAILED
     lseg                 ... FAILED
     interval             ... FAILED
test geometry             ... FAILED
test horology             ... FAILED
     subselect            ... FAILED
     union                ... FAILED
test misc                 ... FAILED

the second time it was only 5:

     abstime              ... FAILED
test horology             ... FAILED
     subselect            ... FAILED
     union                ... FAILED
test misc                 ... FAILED

the third time is was 10 again:
     abstime              ... FAILED
     tinterval            ... FAILED
     inet                 ... FAILED
     comments             ... FAILED
     oidjoins             ... FAILED
test horology             ... FAILED
     case                 ... FAILED
     join                 ... FAILED
     portals              ... FAILED
test misc                 ... FAILED

Results of second and third passes are in the attachment.
It is looks like failed tests are due to
! psql: connectDBStart() -- connect() failed: Connection refused
!     Is the postmaster running locally
!     and accepting connections on Unix socket '/tmp/.s.PGSQL.65432'?

My guess is that this could be due to high load of my box, but
w said
 11:29am  up 24 day(s), 18:30,  2 users,  load average: 0.00, 0.18, 0.29
and I shut down my production postmaster before tests, and I have 256MB of
RAM,
SunOS iridium 5.6 Generic_105181-20 sun4u sparc SUNW,Ultra-5_10
gcc version 2.95.2 19991024 (release)
psql (PostgreSQL) 7.1RC1 (actualy from CVS)

So, the question is: what is the reason of such behaviour, and how to
fight against it?

Regards,
ASK