Unable to get postgres running after long time no vacuum

Hello,

Okay, I was stupid -- I didn't check my database server for a while
(vacation), returned, and found out I didn't run vacuum for a too long
time:

bash-3.1$ psql --version
psql (PostgreSQL) 8.1.9
contains support for command-line editing
bash-3.1$ psql
psql: FATAL: database is not accepting commands to avoid wraparound
data loss in database "tsukku"
HINT: Stop the postmaster and use a standalone backend to vacuum
database "tsukku".

So, I tried to do so, but something weird is going on and I cannot
find out what is going wrong, and how to solve it. I follow the
process of shutting down the database server, and started postgres
like this:

bash-3.1$ postgres --version
postgres (PostgreSQL) 8.1.9
bash-3.1$ postgres -D /var/lib/pgsql/data tsukku

Now, I enter a 'vacuum verbose;' and wait for about a day (the
database is 1TB in size) -- it completes, and I start the database
again; it starts replaying the +- 1K WAL log files for a while, and
after completion, I try to attempt to connect to the database and it
*still* says it is not accepting commands to avoid wraparound data
loss!

The problem also occurs if I just start postgres in single-user mode
instead of the entire service.

What I'm in now is some kind of loop of being unable to get postgres
back up -- anyone has any idea what I can do to find out what the
problem is, and what I can do to solve it ?

Thanks in advance!

Regards,

Leon Mergen