All of a sudden, I cannot upload files in the File Manager. I uploaded two files (~100 KB PDF files) and then on the third, the upload starting hanging (~300 KB PDF). Once I click 'Upload', the progress wheel starts turning, but stays there and the new file is not present. I know my upload quota is enough in PHP because I've been uploading files for two years that are much larger than these without any problem. I haven't made any recent upgrades or changes to Concrete5 or my server and folder settings. Like I said, one minute it worked, the next it didn't.