PG Seg Faults Performing a Query

How would you suggest I try to track down this problem?
I run the following query:

SELECT a.* FROM compliance_2006 a, ers_regions b
  WHERE a.fips_st_cd=b.fips_st
    AND a.fips_cnty_cd=b.fips_cou AND b.region =1
    AND a.fips_st_cd='17' AND a.fips_cnty_cd='003';

and it works. But when I try this:

SELECT a.* FROM compliance_2006 a, ers_regions b
  WHERE a.fips_st_cd=b.fips_st
    AND a.fips_cnty_cd=b.fips_cou AND b.region =1
    AND a.fips_st_cd='17' ;

psql dies with the message:
Segmentation Fault.

Any suggestions?