Everytime I use the crop tool, lightroom freezes up and I have to restart it. Im using PC, with Lightroom CC 2015
Please make sure that Lightroom is updated to the most recent version , Lightroom CC 2015.4
Also please try :
If the solution above from Tanuj helps, you can read through the troubleshooting section of this document for additional insights and potential long term solutions:
In particular, consider trying to update your graphics drivers.