page is blank under 'Welcome' - during installation process, at: ../install.php?profile=default&locale=en

Hello,

I am installing Drupal 6.19 on a Centos 4.7 server with PHP 5.3.0, MySQL 4.1.22 and Apache 2.2.13.

I have the problem that I cannot get beyond the following point during my installation:
I am getting past details for the database, user name etc. I choose the language as english, the url is at this point: '../install.php?profile=default&locale=en'

The display is the typical Drupal layout, with the menu on the left where:

# Choose language
# Verify requirements
# Set up database

have a tick and are green, then the next item:

# Install site

is bold (i assume in progress or the coming step)

The white panel says: 'Welcome' on top and the rest is blank.

Please note there is no error in the apache error log.

Has anyone seen this before?

Thank You in advance.
bianca