install mongodb with node.js: Cannot read property 'arbiterOnly' of undefined

I try to install remotely node.js + now.js + mongoDB on a newly created Ubuntu 11.04 system (64 bits).

I created a structure like this:

• /home/xxx/server.js
• /home/xxx/node/
• /home/xxx/node_modules/now/
• /home/xxx/http/index.html

No problem with node.js and now.js, it works just fine but I have a hard time trying to install and setup mongoDB.

I went to the root of my machine and installed Mongodb this way:

cd
sudo apt-get install mongodb

I don't know if I should but I created a data/db folder like this:

cd
mkdir /data/db
chown `id -u` /data/db

When done, I installed the mongodb driver for node on the appropriate folder:

cd /home/xxx/
npm install mongodb 

Then I started the node server. My static page appears as it should but this is what I get on the ssh terminal after about 10 seconds:

[TypeError: Cannot read property 'arbiterOnly' of undefined]
TypeError: Cannot read property 'arbiterOnly' of undefined
    at /home/xxx/node_modules/mongodb/lib/mongodb/connection/server.js:558:22
    at [object Object].checkoutReader     (/home/xxx/node_modules/mongodb/lib/mongodb/connection/server.js:575:16)
    at /home/xxx/node_modules/mongodb/lib/mongodb/db.js:1344:79
    at Db._executeQueryCommand (/home/xxx/node_modules/mongodb/lib/mongodb/db.js:1555:5)
    at Cursor.nextObject (/home/xxx/node_modules/mongodb/lib/mongodb/cursor.js:455:13)
    at Array.0 (/home/xxx/node_modules/mongodb/lib/mongodb/cursor.js:162:12)
    at EventEmitter._tickCallback (node.js:192:40)
Tue Apr 24 2012 07:12:45 GMT+0200 (CEST) [GET] http://www.verysurf.com/proxyheader.php
error loading file httphttp://www.verysurf.com/proxyheader.php:  { [Error: ENOENT, No such     file or directory 'httphttp://www.verysurf.com/proxyheader.php']
  errno: 33,
  code: 'ENOENT',
  path: 'httphttp://www.verysurf.com/proxyheader.php' }

What is this 'arbiterOnly' error message about? What do I do wrong? I googled this thing but there's not much to find about it.

And that "www.verysurf.com" url at the end of the error message, it's not always the same one. 5 minutes before I got this one (and I didn't change anything, just restarted the node server):

error loading file httphttp://59.53.91.9/proxy/judge.php:  { [Error: ENOENT, No such file     or directory 'httphttp://59.53.91.9/proxy/judge.php']
  errno: 33,
  code: 'ENOENT',
  path: 'httphttp://59.53.91.9/proxy/judge.php' }

I really don't know what these url's are about.

Any help please?

Thank you.