This is caused by getting a bad value from Oracle.
Release : 9.0.2
Component : UIM - ORACLE
Oracle Database 11g Enterprise Edition Release 184.108.40.206.0 - 64bit Production
Please consult with your Oracle DBA to see if the result set of this query ever returns a negative number:
SELECT a.value as db_block_gets,
b.value as consistent_gets,
c.value as physical_reads,
d.value as pr_direct,
e.value as pr_direct_lob,
f.value as pr_direct_temp_space
FROM v$sysstat a, v$sysstat b, v$sysstat c, v$sysstat d, v$sysstat e, v$sysstat f
WHERE a.name = 'db block gets' AND b.name = 'consistent gets' AND c.name = 'physical reads' AND d.name = 'physical reads direct'
AND e.name = 'physical reads direct (lob)' AND f.name = 'physical reads direct temporary tablespace';