Which version of the program is this? On what operating system? What video card do you have?
What model of camcorder is your video coming from and what format and resolution is the video?
Do you have Quicktime 7 installed, per the program's system requirements?
Is this a recent problem or has this been an issue since you first used the program?
Adobe Premiere Elements 10.0 , Mac OSX 10.11.6 El Capitan, Nvidia Gforce GT120 with the latest drivers(346.03.15f04), GoPro Hero 3+, Sony HDR-CX700, Canon Eos 70D, Sony A7
the Videos are MP4, MTS, even JPG's and PNG's don't show up correctly, Resolution is 1920x1080, Quicktime 10.4 is installed.
The Problem exists since i got a Mac Pro 4.1 and i think its a video card problem?!
I suggest you are in the situation of trying to use a five year old version of Premier Elements with a combination of newer operating system, video card drivers and (maybe) cameras. There have been several posts lately concerning various versions and conflicts with Nvidia driver updates. Some have solved it by "rolling back" to old video driver versions.
Updating to the newest Premier Elements apparently fixes things. Please know that projects from the old version may not work with the new version. It has to do with old features that were changed over time. If you try to open an old project, consider opening a copy of it.
I agree with Bill. You're trying to edit some very sophisticated video formats and codecs on some pretty limited software.
Try downloading version 15's free trial and see if you get the same results.