More information needed for someone to help... please click below and provide the requested information
-Premiere Elements FAQ http://forums.adobe.com/thread/1042180
Windows or Mac... box set or download... hardware DETAILS
What computer operating system are you running Premiere Elements 12 on?
What is the exact wording of the error message that you are getting?
In the absence of the above information, I will offer these generalizations for now....
Is your video card driver up to date according to the web site of the manufacturer of the video card? If not, do that.
If it is already at the latest version according to the video card manufacturer's web site, try deleting the BadDrivers.txt file for Premiere Elements 12. Assuming that you are using Premiere Elements 12 on either Windows 7 64 bit or Windows 8 64 bit. the path to it is
Local Disc C
and in the Premiere Elements Folder is a single file among the folders there. That file should be the BadDrivers.txt file that you delete.
Have Folder Option Show Hidden Files, Folders, and Drives active so that you can see that whole path.
Then the routine questions...
Do you have the latest version of QuickTime installed?
Are you running Premiere Elements 12 as Run as Administrator or from a User Account with Administrative Privileges?
If possible, please post a screenshot of the error message that you are getting when you go to open Premiere Elements 12.