Nobody can know. You have not provided any system information. The bad news is that runtime errors point to severe system problems like missing DLLs or a generalyl unsuitable configuration.
IF you are on Windows (your really need to provide more information when asking a question) read below
Some of this may be for Premiere Pro, but SHOULD also help with Premiere Elements
Also http://www.microsoft.com/en-us/download/details.aspx?id=14632 for a Microsoft download
Also search http://search.microsoft.com/search.aspx?mkt=en-US&setlang=en-US for Microsoft help articles
What computer operating system is your Premiere Elements 12 running on?
What are you doing in the project when you get this error?
Program: ...e\Adobe Premiere Elements 12\Adobe Premiere Elements.exe
abnormal program termination
To put that in context
a. What are the properties of the source media that you have imported into the project? Brand/Model/Settings for camera that recorded the source media would be a start...photos and videos?
b. What is the project preset that you or the project has set based on the properties of that source media?
c. What is the duration of the Timeline when the error hits?
d. What is the description of your computer resources...installed and available RAM, free hard drive space, as well as where your scratch disks are directed and how much free space is at the location(s) to which they are directed?
e. Have you done any deactivate, uninstall, reinstall of the program yet or deleted any settings file?
The answers to the above will be a start to getting at the core of your issue.
You might want to check out the following Adobe document on Adobe Products Windows and Run TIme Errors
In that context...assuming that your Premiere Elements 12 is on Windows 7, 8, or 8.1 64 bit....Delete the Adobe Premiere Elements Prefs file (aka settings/preference file)
Local Disk C
and in the 12.0 Folder is the Adobe Premiere Elements Prefs file that you delete. Be sure to be working with Folder Option Show Hidden Files, Folders, and Drives active to see the complete path cited.
Lots to consider. We will be watching for your progress.