There is another recent thread on this same message. No answer found yet in that case.
What version of Premiere Elements and on what computer operating system is it running?
When does this message appear, when you open a new project or when you add media to the project's Timeline?
Do you also get this message if you open a project that you have worked on and saved closed?
Do you have an Adobe Creative Suite applications on your computer at the present time? Or, have you recently installed uninstalled Adobe Creative Suite application(s)?
For now, please do a free ccleaner run through using the regular as well as the cleaner part of this cleaner. This cleaner is not the Adobe CC cleaner. The ccleaner that I point to has a different source and has a history of effectiveness for non Adobe and Adobe products.
If that does not provide a solution, then please
1. Uninstall the program the usual Control Panel way
2. Do the free ccleaner run through (regular and registry cleaner parts)
3. Reinstall with antivirus and firewalls disabled.
Please review, consider, and supply more information. If you have any questions or need clarification on the above, please do not hesitate to ask.