pg_ctl: server does not shut down

Hi,

My production server is running PostgreSQL v8.2.3 on CentOS release 5.2
(Final).

I've setup PITR in my production server. For some reason, after setting up
PITR, we're not able to manage and maintain it.

PITR SETUP DETAILS
We've 2 drives. Primary drive (pgsql/data/ directory resides) is 400 GB and
secondary drive (WAL archive) is 300 GB. All WAL archives are written to
secondary drive.

Base backup taken on: Aug03, 2009
WAL archive drive become full (100% use) on: Jul01, 2010

Because this WAL archive drive has become full, all WAL archive segments to
be archived are accumulated into pg_xlog/ directory itself. Eventually,
almost 4 months (as of today from Jul01, 2010) of WAL archives are residing
in pg_xlog/ directory.

ISSUE
We then decided to stop PITR in our database. Steps which I followed are:
1. service postgresql stop
2. Detached (unmounted) 300 GB secondary drive (WAL archive)
3. Disabled WAL archiving by commenting (#) 2 postgresql.conf parameters:
"archive_command" and "archive_timeout".
4. service postgresql start

Now, the database has started without any issues. But when I tried to stop
database using 'service postgresql stop' within few minutes after it's been
started, it was not shutting down and responded with the following message
after few minutes:
"Stopping PostgreSQL: pg_ctl: server does not shut down"

I even checked serverlog for whether any errors/issues are reported, but I
don't find any. Also, when I tried to login to my database at this time, it
says:
psql mydb mydbuser
psql: FATAL: the database system is shutting down

but not actually shutting down ever. I'm clueless why it is happening so
and not shutting down ever.

My questions are:
1. What could be the root cause of PostgreSQL server not shutting
down ever?
2. Am I following a different/incorrect way of disabling PITR?
3. Considering this situation, now how do I safely disable PITR in
my database?

Experts advice/idea/suggestion on this are appreciated.

Regards,
Gnanam