Vacuum hangs

PG: 7.4.5
RH 7.3
Vac_Mem=12mg

Doing a Vacuum Analyze on a table and it's been hanging for at least 2
hours. I could see no other users hitting the table at the time. This is
the second time this has happened on this particular table and I can't
seem to pin point the issue. If I kill the PID and restart the vacuum
analyze it works fine. Any suggestion where I start searching? Here is
an output from pg_stat_activity and the

mdc_oz=# select * from pg_stat_activity:
datid | 17145
datname | mdc_oz
procpid | 16560
usesysid | 2
usename | phatcher
current_query | VACUUM ANALYZE cdm.cdm_reg_customer;
query_start | 2004-11-09 10:02:32.523146-08

mdc_oz=# select * from pg_locks where pid=16560;
-[ RECORD 1 ]-------------------------
relation | 7059380
database | 17145
transaction |
pid | 16560
mode | ShareUpdateExclusiveLock
granted | t
-[ RECORD 2 ]-------------------------
relation |
database |
transaction | 28863986
pid | 16560
mode | ExclusiveLock
granted | t
-[ RECORD 3 ]-------------------------
relation | 7059380
database | 17145
transaction |
pid | 16560
mode | ShareUpdateExclusiveLock
granted | t

TIA

Patrick Hatcher