It depends on where those MOVs are coming from. MOVs, like AVIs, can use any of hundreds of codecs, and only a few are compatible with Premiere Elements.
MOVs from still cameras often use the MJPEG codec, which Premiere Elements can not work with.
And do make sure you have the latest version of Quicktime, of course, per the program's requirements.
Welcome to the forum.
As for those MOV files, well, they can contain almost anything, and knowing the exact specs. of them, will be very useful. This ARTICLE goes into more detail.
For issues with PrE, then this ARTICLE starts with a general checklist of things to look into, and if those do not fix things, then there are many links on troubleshooting, basically working up in "degree of difficulty."
thank to Steve and Bill for your helpful answers.
OK the *.mov files are from a Canon EOS 500 and/or a Canon Powershot A540.
When I understand you right I can´t use Prem elements to edit files from this cameras.
Bill has a formula that sometimes works. But generally and as a rule, no, you can't edit MJPEG-MOVs in Premiere Elements. The best program to do this in is Quicktime Pro, which costs $29 from Apple.com.
The good news is that your Canon Powershot may shoot in MJPEG, but your EOS doesn't!
So, if your set your project up using one of the project presets for DSLRs, you should be able to edit the video from your DSLR. Note, though, that your DSLR shoots in 640p, 720p and 1080p -- so make sure that the project setting you choose matches the mode you shot your video in.
If one camera IS MJPEG, this ARTICLE might be useful.
With mixed footage, I feel that the best workflow is to create one separate Project for each type of Source Material, and then Export/Share from one of those, to match the specs. of the Source Footage in the other - just Export/Share (choosing the right file specs.) and then Import that resultant output file into the other Project.
PrE does not do so well, with mixed Source Footage. Now, PrPro, as of CS5, and the current CS5.5, does much better, with the MPE (Mercury Playback Engine) and CUDA support. However, that is not a "cheap" solution, and doing the separate Projects first, then outputting one to match the other, is almost always a good solution, and is far, far cheaper - just a few extra keystrokes and mouse clicks.