What version of the program are you using and on what operating system? Have you gone to the Help menu and checked to see you have the latest updates?
Have you ensured you have the latest version of Quicktime, per the program's requirements?
What are you doing when you see this error? Are you trying to open RAW files?
Also, can you confirm that you're getting this issue in Premiere Elements rather than Photoshop Elements?
The download is probably corrupt.
Disable anti virus and firewall and try again.
And please do not double post, thread locked.
Please continue in this thread
Is this PE9 we are talking about?