Error 404 after upgrading to PHP 5.4

Hi.
On a Debian7 server I run some static sites and some PHP applications; Prestashop, Drupal 7 and 2 sites in WP latest versions. I recently upgraded from Debian 6 to 7 with no problems. As I had manged to screw up Apache at an earlier stage and I made a full reinstall of Apache2 and PHP 5.3 after fist having purging them. At the reinstall it turned out that the Apache stayed on the old version number (2.2.22) while PHP upgraded from 5.3 to 5.4. It was now the problems occuered: The static sites worked perfectly well, Prestashop 5.6.4 was down, Drupal7, had big problems, among them I couldn’t login and both WP sites was down.

Prestashop caused this message in the log:

.htaccess: Invalid command ‘RewriteEngine’, perhaps misspelled or defined by a module not included in the server configuration

Seraching on that message Google found and answer to me and that was to tell Debian

ln -s /etc/apache2/mods-available/rewrite.load /etc/apache2/mods-enabled/rewrite.load

And voilà! Suddenly everything was fine. Except for one of the WP sites that remaind down. I couldn’t even access it over /wp-admin . It wasn’t untill I deleted the .hataccess it started to move. Now I can reach the first page and and /wp-admin, but no other pages. All other pages gives 404 and the the Apache2 error log says

[Mon May 11 12:40:29 2015] [error] [client 88.166.231.21] File does not exist: /var/www/lions/valdeurope/wordpress/actualites, referer: https://www.lionsclub-valdeurope.org/

So what is going on? What is the problem with this site??? Below is the .htaccess I killed. NOTE, the other WP-site, the one that works, never had any .htaccess

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

Please help.

Hans