[TYPO3] symlinks - cannot find tslib/ in $configured_tslib_path - problem

[Bryan]

Hi there Guys, and girls, just wanted to find out more about these
symlinks as I'm having a weird problem which seems to be related to
version 4 and above.

I've found a few other posts but nothing concrete to resolve it correctly:
Cannot find tslib/. Please set path by defining $configured_tslib_path
in index.php.
Here is the situation: when I open the URL like so:
http://192.168.0.1/site-name/index.php
it works fine, but when I go directly to the site:
http://www.site-name.com/index.php
I get this error.

Now I know it's got something to do with symlinks and the main problem
is the 'tslib' which isn't there any more or moved.

It's a clean typo3_src-4.0.1 install with the dummy site.

Any idea's. I'm a newbie to Typo3 but learning slowly.
Thanks Bryan