How did I fix questions marks PHP ouput?

02

I fixed it with zend_optimizer.enable_loader = 0.
stackoverflow.com/a/4854031.

It seems that after a successfull page load Zend Optimized can be re-enabled again: zend_optimizer.enable_loader = 1.

The issue seems to be related to a corrupted PHP file (it could be corrupted by a storage drive failure).