PHP broken after Instalation

[kts]

Hello,

upon installing ispcp PHP appears to be somewhat broken. When I open php files in my browser, I just get blank, white pages. However, opening the ispcp panel, I receive some sort of a downloading dialog and it says something like "application/x-httpd-php". I've checked my apache configuration and modules list and PHP5 is said to be running just perfectly. I honestly got no clue what this is about, as before the installation php worked.
I'm running on Debian Etch 64Bit.

I'd really appreciate it, if someone could help!

Thanks in advance,
kts