Headers already… in line 1 in install.php

I’m using the Danish downloaded version 2.2 on a Debian with SQL 5.0.32.

I keep getting this error on the first page of installation:

Warning: Cannot modify header information – headers already sent by (output started at /usr/local/psa/home/vhosts/xxxxxxxx/subdomains/blog/httpdocs/wp-admin/install.php:1) in /usr/local/psa/home/vhosts/xxxxxxxx/subdomains/blog/httpdocs/wp-admin/install.php on line 15

I’ve tried to edit both install.php and config.php – but there are absolutely no whitespaces.

When I go further to the 3rd page, I’m being told that WP needs MySQL 4.0.0 or higher (and I have the 5.0?)

I’ve tried searching for these answers in the forum – but noone matches the problems I’m encountering.