What version of Premiere Elements and on what computer operating system is it running?
Have you used those Canon 7D files in yourPremiere Elements/computer operating system before?
The MVI to which you refer, I believe, is part of the Canon 7D file name. The file is probably AVCHD.mov.
First question then becomes "Do you have the latest version of QuickTime installed on your computer with Premiere Elements and are you running the programs as administrator?
Let us start here. Then we will decide what next based on the details in your reply.
The answers will be in the details.
Any questions or need clarification about the above, please do not hesitate to ask.