No logo, favicon or CSS

Hello

On a fresh install (no modules other than core ones), I can't see any new logo or favicon, and CSS doesn't show up when using color enabled themes...

From what I can see, there is something weird in the HTML of the pages:

Favicon:
<link rel="shortcut icon" href="//var/www/vhosts/mydomain.com/httpdocs/files/garland_favicon_1.ico" type="image/x-icon" />

Logo:
<img src="//var/www/vhosts/mydomain.com/httpdocs/files/garland_logo.gif" alt="My Domain" id="logo" />

CSS (when using a different color than default):

<link type="text/css" rel="stylesheet" media="all" href="//var/www/vhosts/mydomain.com/httpdocs/files/color/garland-6ce5b5d3/style.css?q" />

Why "//" at the begining of these URLs ?

Same thing whatever the theme is (Garland, Pixture...)

Drupal: 6.8
PHP: 5.2.0-8+etch13
MySQL: 5.0.32
Apache: Apache/2.2.3 (Debian) mod_python/3.2.10 Python/2.4.4 PHP/5.2.0-8+etch13 mod_ssl/2.2.3 OpenSSL/0.9.8c mod_perl/2.0.2 Perl/v5.8.8

Public filesystem
files: /var/www/vhosts/mydomain.com/httpdocs/files
tmp: /tmp