Moving this discussion to the Premiere Elements forum.
Meantime, please provide some basic information:
What is your operating system?
What processor are you running, how fast does it run and how much RAM do you have?
How much free, clean, defragmented space is on your hard drive(s)?
What model of camcorder is your video coming from and what format and resolution is it? How did you get this video from the camcorder to your computer?
When you start a Premiere Elements project, what project settings are you selecting?
Since apparently this is a new issue, what changed on your system prior to this happening?
I have windows 7 Quad core. I've been creating videos for about a year using the Adobe Premiere Elements 10. Only recently have I encountered this issue.
I may have found the source, but not sure what the root cause is. I have a Go Pro HD2 camera and have used APE as my editing source. However, I recently used Go Pro Cineform Studio to add additional color. Afterwards, I converted the video back to MP4 Video. This was where I encountered the problem.
It seems there is an interface issue using Go Pro Cineform with APE.
I was able to restore the video to the original version. APE 10 is now accepting the video.
Does APE 10 have the capability to edit video footage to increase color, sharpness, etc.?