What version of Premiere Elements and on what computer operating system is it running?
Is this a "it worked before but not now" or a "it never worked before".
You have not supplied enough information for us to help you. Please give us details to help us to help you.
What are the properties of the files that you are importing into the project? Are you working with iTunes music?
What is the project preset that you (manually) or the project (automatically) is setting to match the properties
of the source files?
Other questions include:
1. Are you running the program from a User Account with Administrative Privileges?
2. Do you have the latest version of QuickTime installed on your computer with Premiere Elements? Does the
problem exist if the computer's antivirus and firewall(s) are disabled?
3. What are the details of your export choice(s) for your Timeline content?
4. Are there any error messages associated with any of these problems?
5. Others, including details of computer resources and setup of Scratch Disks.
Lots to be sorted out to get to the core of the problems.
If any questions or need clarification on the above, please do not hesitate to ask.