No PHP pages working accept for admin

[AcE_IoXx]

Hello,

Yesterday I decided to upgrade my server (was running Debian sarge testing with vhcs2).
So I installed a new version of Debian Etch (stable). (formatted the disks)
Installed IspCP according to the Debian how-to on this site.
Decided to make the accounts again instead of restoring them from vhcs2.

Made all the accounts again uploaded all the sites.
Made sure php is enabled in the accounts

All the HTML sites are working.
But ALL the php sites are showing the same error, namely: No input file specified.

I googled a lot but couldn't find an answer to this problem, so now I'm asking if anyone here knows how to solve this problem.

All the configuration files are still standard as IspCP setup leaves them.
If you need any config files or log files, just ask me which ones and I'll post them here.