Hi there, Robert!
Thanks for using the Apple Support Communities! After reading your post, I understand that when you connect your Thunderbolt display to your new MacBook Pro, the Mac will become unresponsive or will unexpectedly restart. I know how convenient having an additional display can be for a MacBook Pro, and am happy to help by providing some troubleshooting steps you can take!
First, try resetting the computer's NVRAM while the display is connected. The following article will give you some more information on what the NVRAM is, and how to reset it: How to Reset NVRAM on your Mac
After resetting the NVRAM, try using your Thunderbolt display with the MacBook Pro. If it's still causing the Mac to become unresponsive or to unexpectedly restart, test its performance in a new user account. You can get more information on why testing in a new user can be helpful, and instructions on how to set up a new account if you need it, in this article: How to test an issue in another user account on your Mac
If the display and Mac still do not work as expected together while in a new user, the next recommendation I have would be to reinstall your OS X software. If you do not already have a backup of the content currently on your Mac, please create one using Time Machine first. Instructions on how to set up and use Time Machine can be found here: Use Time Machine to back up or restore your Mac
Once your backup is complete, you can use the following article to help erase your Mac, and reinstall your OS X software: How to reinstall OS X
After reinstalling OS X, test your Thunderbolt display. If you continue to have trouble with it, you can run an Apple Hardware Test to see if there's something physical going on to cause the issue. Instructions on how to do the hardware test can be found here: Using Apple Hardware Test
You can also take a look over the following article, which will give some additional information and support regarding external displays: Get help with video issues on external displays connected to your Mac
Cheers!