ERROR: canceling query due to user request

Hello.

I am trying to port an old java application from MS SQL Server to
PostgreSQL running on Mac OS X. I have access to the java source code
and can make modifications. I have tried with PostgreSQL version 7.4.2
and 8.0.0beta2, but get the same error. I am using pgdev.305.jdbc3.jar
for 8.0.0beta2. The PostgreSQL installation are standard, except for
log_statement = 'all' to debug this problem.

The problem is that the server returns "ERROR:  canceling query due to
user request" on some of the queries. I do not find any (other) signs
of small timeouts or that the query could be cancelled in the java
client. I have tried the queries from the psql promt, and they are all
pretty fast. Where should I start looking? Are there any more debug
flags than log_statement that should be turned on?

Regards,
  - Tore.