I have not read of PE12 problems with NVidia... but, you may try an older NVidia driver as discussed below
•nVidia Driver Rollback PreElements-10 http://forums.adobe.com/thread/1317675
•-Old Drivers http://www.nvidia.com/Download/Find.aspx?lang=en-us
The Premiere Elements 10/NVIDIA GeForce issue has been to this moment specific for Premiere Elements 10.
You should not expect to find this problem using a Premiere Elements version other than 10.
Please read the Announcement at the top of this forum which details the issue and the how to fix.
Please give your computer operating system, including 32 or 64 bit. For Windows 8 or 8.1, there may not be an
old enough driver version for you to use to fix the problem. The roll back needs to be to about May 2013.
Copy/Paste of Announcement for your convenience
Premiere Elements 10 NVIDIA Video Card Driver Roll Back
If you are a Premiere Elements 10 user whose Windows computer uses a NVIDIA GeForce video card and you
are experiencing Premiere Elements 10 display and/or unexplained program behavior, then your first line of
troubleshooting needs to be rolling back the video card driver version instead of assuring that it is up to date.
Since October 2013 to the present, there have been a growing number of reports about display and unexplained
workflow glitches specific to the Premiere Elements 10 user whose Windows computer has a NVIDIA GeForce
video card. If this applies to you, then the “user to user” remedy is to roll back the NVIDIA GeForce video card driver
as far as is necessary to get rid of the problems. The typical driver roll back has gone back as far as
March – July 2013 in order to get a working Premiere Elements 10. Neither NVIDIA nor Adobe has taken any
corrective action in this regard to date, and none is expected moving forward.
Since October 2013, the following thread has tried to keep up with the Premiere Elements 10 NVIDIA reports
Older NVIDIA GeForce drivers can be found http://www.nvidia.com/Download/Find.aspx?lang=en-us
A February 2014 overview of the situation as well as how to use the older NVIDIA GeForce drivers for the
driver roll back can be found http://atr935.blogspot.com/2014/02/pe10-nvidia-video-card-roll-back.html
Please review and consider. We will be looking forward to your follow up.