I'm having an issue with my UR5e robot where after starting up a program the controller screen freezes and needs to be restarted to have any access to control the robot. The cobot will continue to run without issue unless it crashes or the e-stop is pressed. If one of those conditions occurs the robot will stop but we have no way to restart it without rebooting the controller. We have 2 main programs that we run and the issue only seems to occur on the longer more complicated one so I'm assuming its something in the program causing it to freeze. Within that program we have a number of variables being tracked and we are using the robotiq force copilot UR-cap as well. Has anyone else run into an issue like this and have any suggestions on how to troubleshoot it? We see it occur about 2/3 of the time when running that program right now. 

@MJF
Did you tried to contact UR support team ?
Are you using Robotiq products in your application ?

It could be that your program is too heavy and challenges controller specification. You may solve this kind of problem with a lighter program.
Reducing thread can for example help to save some controller ressource.

The only time we’ve really seen the pendant on e-series lock up is when logging lots of messages to the log using the textmsg() function. Other than that, look for any issue in a thread where you are performing very heavy computations, lots of string manipulation, etc. 

Another thing to try is upgrading to the latest version of Polyscope as they have been working to reduce the memory intensity of Polyscope to help with these controller freezing situations.