There are a variety of issues related to Error 16 which are troubleshooted as Premiere Elements issue in the Premiere Elements Forum. Most often you see it addressed as a permissions issue.
What computer operating system is involved? Have you updated Premiere Elements 12 to 12.1 using an opened projects Help Menu/Updates? Are you still using Windows 8.1 or have you upgraded to Windows 10 as per your recent thread about computer operating systems?
Please clarify...was Error 16 happening every 3 months with Premiere Elements 12/12.1 on Windows 8.1 and escalated to weekly happening when and if you upgraded to Premiere Elements 12/12.1 on Windows 10? Or have you remained with Windows 8.1 all this time?
What are you doing in the program when you get this Error 16 message? Does it block you from continuing in the project? Since this seems to be a re-occurring error for you, first every 3 months and now weekly, is uninstalling reinstalling the program the only way that you have found to resolve the problem so that you can move on in your project? Have you ever deleted the Adobe Premiere Elements Prefs file at one of these Error 16 events?
When it occurs, please go to the Event Viewer and look for a description of the error.
Check Adobe folder permissions, such as the Adobe Folder in the path Documents/Adobe/Premiere Elements/12.0 ---See Adobe Folder and its Security Tab.
Also, run the free ccleaner (regular cleaner and registry cleaner parts) as alternative to uninstall reinstall.
Assuming that your computer system is Windows
if uninstall reinstall become necessary, then uninstall, free ccleaner (from the link above...this is not the Adobe CCleaner and then reinstall with antivirus and firewalls disabled.
Please consider. Any questions or need clarification on the above, please do not hesitate to ask.