Our organization has a Visualforce page, exposed through sites, that allows users to upload a file. When uploading .pdf files, users receive the generic authorization required error. They can, however, upload other file types without a problem. Is there any particular restriction on the uploading of .pdf files that I'm not aware of? I've checked the debug logs but there were no errors that I could see. Any help on how to troubleshoot this would be much appreciated.
Edit: The error I get when viewing the page as a logged in Salesforce user is below.
*Maximum view state size limit (135KB) exceeded. Actual view state size for this page was 156.188KB *