After upgrading to 1.8.3+ from 1.8.2+, all of the user profile images have "disappeared." The correct images are still on the server and still located under moodledata/users/NN/f1.jpg, f2.jpg. However, these images no longer display when pulling up the student list in a course or looking at a particular student's profile. In both cases, Moodle is displaying the generic user icon for everyone.

This has never previously happened to us after any other upgrade of Moodle. However, just for the sake of checking, I turned off slash arguments (which has always been on in the past), but that did not make a difference either.

Here's the part that's confusing me - when I pull up the picture properties, the path (user/pix.php/13/f1.jpg) shows that it should be pulling up the custom image as it's pointed right at it. However, in every case, it's still the generic one. Is this an issue with pix.php? Something else?

I have verified that this is not a caching issue with the browser. I have tried with both Firefox and IE, both having cleared the cache completely, both having reloaded the pages, etc.