Sorry but you haven't given us nearly enough information to be able to help you.
What operating system are you using? How fast is your processor and how much RAM do you have? How much free, freshly defragmented space is on your hard drive?
Have you manually gone to Windows Update and ensured you have even the non-critical updates? Have you gone to the ATI or nVidia web sites and ensured you have the latest firmware for your graphics card? Do you have the latest version of Quicktime?
What type of camcorder is your video coming from and how did you get it into your computer? Which project settings did you select when you set up your Premiere Elements project?
As you can see, there are a number of possible causes for your problem.
The first thing that I would do is work through the tips in this ARTICLE. Do not ignore the links inside, especially the "Clean, Lean, Mean Editing Machine" link.
If this not cure the issues, then see this ARTICLE for the types of info that would be so helpful in diagnosing the problem.
Good luck, and please report back,