System freezes while using thunderbird on Laptop-Display

Hi, since a few days, I have a big problem. This is my setup: - Lenovo Thinkpad L450 - Ubuntu 16.04.3 LTS - DisplayLink Linux Software 4.1.9 - i-tec USB 3.0 Dual Docking Station - 2x iiyama ProLite E2480HS Monitor 1 is above laptop display Monitor 2 is right-of Monitor 1 Monitor 1 is primary (Taskbar, Startmenu, etc...) Since a few days, my whole system freezes, when I switching a folder in thunderbird, but only when thunderbird is shown on laptop display. If thunderbird is shown on Monitor 1, i can change folders. If system freezes, I only can switch off the laptop, start again. Thunderbird is the only programm that makes this troubles. After restart I ran "sudo ./DLSupportTool" and attached the zip file. Thanks in Advance best regards Martin

Update 

It's not just thunderbird... Today, Skype was on Laptop Monitor. I open "Send File" and system freezes :-( Maybe there are more software affected.

Hi, Did you upgrade anything recently? Especially X and related packages? Cheers, Michal

I see the kernel has been upgraded, and some mesa packages as well. Can you check if disabling intel_mmu helps? Cheers, Michal