Does the problem exist with and without the antivirus and firewall(s) disabled?
Have you updated from 12 to 12.1 Update? If not, please do so, using a project's Help Menu/Update.
When you go to Publish+Share/Computer/QuickTime, do you find presets for the QuickTime choice? If so, what are they?
Go to Edit Menu/Preferences/Web Sharing and refresh the Online Services?
Next, if problem not resolved...delete the Adobe Premiere Elements Prefs file and, if necessary, the whole 12.0 Folder in which the Adobe Premiere Elements Prefs file exists.
Local Disk C
and in the 12.0 Folder is the Adobe Premiere Elements Prefs file that you delete. If that does not work, then we delete the whole 12.0 Folder in which the Adobe Premiere Elements Prefs exists. Be sure to be working with Folder Option Show Hidden Files, Folders, and Drives active so that you can see the complete path. In Windows 8.1, I believe that the path to Folder Options starts with File Explorer.
Please review and consider and then let us know if any of the above works for you. More later.
- delete Adobe Premiere Elements Prefs: does not help
- delete the whole 12.0 Folder: worked for me! - thank you very much!
- for others who look for the Folder Option Show Hidden File button in windows 8.1: