We would need more information on what is freezing and what is happening when that happens. Was the UI built using Pega Robotics Studio, or it it your own custom component you are using? You would likely need to enable Runtime logging to determine what is happening when it freezes. I would also ask the users to identify which specific steps they were executing at the time. You might be able to reproduce the issue which would make it easier to troubleshoot.
One common thing that is reported as a freeze is when you are executing automations off of your UI synchronously (meaning in the same thread). This makes your UI unresponsive until the thread completes. Make sure all of your links off of your UI are asynchonous (i.e. dotted lines).
Another common method of freezing your UI can happen when you have DataGrids and are not updating them off of the UI thread. This requires a posting of its own to explain, but if you do have DataGrids, let me know and I can provide some direction on easy ways to ensure they are only updated on the UI thread.
This issue seems like it must be specific to your solution. I would suggest you open an SR to have someone examine your issue. If you do open an SR, please update this post with the SR number for tracking purposes.