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