Adobe Premiere Pro CS6 Freezing

I am experiencing freezing issues when trying to edit within premiere pro. Simple tasks like cropping videos, color correcting or anything done to the video will freeze the program window and then eventually freeze the program.

System Specs:

Model Identifier:          iMac12,1

  Processor Name:          Intel Core i7

  Processor Speed:          2.8 GHz

  Number of Processors:          1

  Total Number of Cores:          4

  Memory:          12 GB

Using Premiere Pro CS6 6.0.2

Any help appreciated!