>explain this to me as simple as possible
I don't think there IS a simple answer... video editing is a complicated process, so you are going to have to provide more information before someone can help
From the Premiere Elements Information FAQ http://forums.adobe.com/thread/1042180
•What version of Premiere Elements? Include the minor version number (e.g., Premiere Elements 9 with the 9.0.1 update).
•What operating system? This should include specific minor version numbers, like "Mac OSX v10.6.8"---not just "Mac".
•Have you installed any recent program or OS updates? (If not, you should. They fix a lot of problems.)
•What kind(s) of image file(s)? When talking about camera raw files, include the model of camera.
•If you are getting error message(s), what is the full text of the error message(s)?
•What were you doing when the problem occurred?
•What other software are you running?
•Tell us about your computer hardware. How much RAM is installed? How much free space is on your system (C:) drive?
•Has this ever worked before? If so, do you recall any changes you made to Premiere Elements, such as adding Plug-ins, brushes, etc.? Did you make any changes to your system, such as updating hardware, printers or drivers; or installing/uninstalling any programs?
And some other questions...
•What are you editing, and does your video have a red line over it BEFORE you do any work?
•Which version of Quicktime do you have installed?
What is your exact brand/model graphics adapter (ATI or nVidia or ???)
What is your exact graphics adapter driver version?
Have you gone to the vendor web site to check for a newer driver?
For Windows, do NOT rely on Windows Update to have current driver information
-you need to go direct to the vendor web site and check updates for yourself
ATI Driver Autodetect http://support.amd.com/en-us/download/auto-detect-tool
nVidia Driver Downloads http://www.nvidia.com/Download/index.aspx?lang=en-us
Do you have a computer with dual graphics adapters?
Go to the Windows Control Panel and select Hardware and Sound and then select Device Manager... In Device manager you click the + sign to the left of Display Adapters... and see if 2 are listed
IF YES, read below... (some for Premiere Pro, but the idea is the same)
-link to why http://forums.adobe.com/message/4685328
What computer operating system is your Premiere Elements 12 installed on?
Please describe its resoures, such as installed and available RAM and free hard drive space.
Is this a "it worked before but not now" or "it never worked before situation"? How did you install the program, from online download or from an installation disc?
Do you have the latest version of QuickTime installed on your computer along with Premiere Elements 12?
Are you running the program from a User Account with Administrative Privileges (See Control Panel/User Accounts to verify the account that you are running the program from)
If you do not already know, please look at Device Manager/Display Adapters/ and tell us how many video cards/graphic cards you see listed there. What are their names? Check the driver(s) for the video card/graphic card to make sure that it is up to date according to the web site of the manufacturer of the card or according to the web site of the manufacturer of the computer.
There are lots of possibilities for the program situation that you describe. The typical troubleshooting drill needs to be gone through to rule in or out factors as we try to get to the solution.
I will suggest the next phase once you review and consider the above.
Looking forward to your follow up.
Thanks for posting on Adobe forums.
1. Could you please provide me error log from the eventviewer ?
2. Does it happen every time ?