RC7 -> 1.0.0 - Permission denied

[DaSilva]

I cannot completely remove it because it is a productive system.
Now I have seen that it is a global problem since the update to 1.0.0.
A customer had problems with rights in a session directory, too.
I had to manually set it to user www-data and then it worked.
I think I know now why this has happened. After the update .php pages were not displayed but provided to download. .html pages were ok. So I manually installed libapache2-mod-php5 and .php pages were displayed correctly again. This must be the problem but I don't know how to solve it, please help!