What computer operating system is involved with your Premiere Elements 11?
Are you in the Expert or Quick workspace? What Add Media choice are you using? Do you get the same result in Expert and Quick workspaces?
What are the properties of the file that you are trying to import into the project? What is your project preset?
Do you have the latest version of QuickTime installed on your computer with Premiere Elements 11, and are you running the programs as administrator (from user account with administrative privileges)?
Does the problem exist with or without antivirus and firewalls disabled?
The answers are in the details.
Please consider, give more details, and then we can decide on troubleshooting strategy.