What computer operating system is your Premiere Elements 13 running? Have you updated 13 to 13.1 yet using an opened project's Help Menu/Updates? If not, please do that.
What are the properties of your video files for this project - brand/model/settings for the camera that recorded the video might be a quick and easy way to get at that important troubleshooting information. What are you (manually) are the project (automatically) setting as the project preset to match the properties of the video?
What is the duration and complexity of the Timeline when the project freezes and what are you doing in the Timeline when the project first freezes? If you go to a new project, do you have the same issues
a. if new project and same videos
b. if new project and new videos
Have you gone through the usual drills
a. Does problem exist with or without the antivirus and firewalls disabled?
b. Do you have the latest version of QuickTime installed on your computer with Premiere Elements, and are you running the programs as administrator?
c. Is your video card/graphics card driver version up to date according to the web site of the manufacturer of the card or manufacture of the computer?
Please describe your computer resources.
Let us start here, and then decide what next based on the details in your reply.