Hello Darius,
Your remark of MTU 1600 triggered it for me. Indeed not the upgrade as such. Although IMHO VMware image shouldn't crash on it, but you mentioned that already ;-).
I had from a config template indeed mtu set to 1600.
I changed that to mtu 1536 and even with now again dot1q on it works. And no more VMWare crashes either.
I want to have a minimal payload of 1500 IP bytes + 20 bytes IP header + 8 bytes dot1q + (2 * 4 bytes MPLS label) makes 1536 as minimum for the L2 Ethernet frame.
I changed that and even all works for the B2B directly connected working interface, redundancy interface 
I will see later back for the other interfaces that will also run MPLS between each other.
So for others remember this one regarding MTU Size do not pass beyond 1600 or VMware Workstation crashes due the vmxnet3 driver.
Thank you again for your help.