Hello
There have been some problems in using MP4 and Mov, Corel have brought out a Hot fix available from their web support pages, however I did have problems downloading from Corel.
http://howto.corel.com/en/corel?family= ... mp4lib.dll
There are many different types of Mov and MP4 video files so I am not sure if this fix covers your particular files but is worth a try.
I have attached the file and install info to this post