I ran SiteSurvey and it found a CPU incompatibility. So I will not go further with this test...
I have finally found the solution for this problem. I replaced the "VMXNET 3" network card by a "VMXNET 2 (Enhanced)" one. I works perfectly like that even with non compatible CPUs !!!
Yes, Vmxnet3 nics do not work with FT yet.
Vmxnet3 support for FT will come in a future release.