System freezes while using thunderbird on Laptop-Display

[dj-digger]

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