Hello and thank you for asking your question, with JustAnswer.com/Mac. I am Sr. Mac Tech Support Specialist, Terry, glad to assist you.
Here are some steps you can try to resolve the issue:
• First, hold in your power button for approximately 10 seconds to do a hard shutdown.
• Once your Mac is shutdown, you will need to perform what is called a PRAM reset (Parameter RAM)
This should help with the freezing issue:
• Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously .
• Turn on the computer.
• Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
• Now, hold the keys down until the computer restarts and you hear the startup sound for the third time.
• Release the keys and allow the Mac to start up.
• Please update me to let me know if this works.
I see you are offline. When you are back online however, just reply back to this session, I will be alerted, whether I am online or off and will be able to assist you further.
Thanks for posting your question, I look forward to assisting you shortly.