Im stuuuuck, and cannot find out what I am doing silly, see screenshot.
Thanks for any hints…
firmware mismatch!
Hints are in the Output window. And as Mike said it is a mismatch.
it is “a3000000” 
FezConfig Output:
Loader (TinyBooter) version information:
4.3.4.0 on this computer.
4.3.4.0 on this device.
The Loader (TinyBooter) is up to date. <<<
Firmware (TinyCLR) version information:
4.3.4.0 on this computer.
4.3.4.0 on this device.
The Firmware (TinyCLR) is up to date. <<<
I am not sure what your comments mean exacltly.
New project in VS2012 with 4.3 as version when created.
Is it because the Cobra II is not supported by GHI anymore?
Visual Studio is trying to load 4.3.3 assemblies. References are stale.
Makes sense, but what to do?
Remove references and re-add them. Keep an eye on the version number of added references. If you are adding a prebuild non-SDK assembly, make sure it is build against the same version of the NETMF/Firmware
That sounds really silly. Its a NEW project…
Well, from the picture you have posted only two assemblies are “old” - NullModem and FezCobraIIEcoExtender.
I’m having the same problem with a Cobra II WiFi on my laptop. Just tried it on the desktop machine which was reformatted etc last week and noticed that the Cobra II WiFi isn’t listed as a mainboard (see images for the difference between the two).
I was pretty sure that I had done a clean install on the laptop as well but it’s now left me wondering.
Which leads to my conclusion: the r3 installer does not always remove earlier sdks.
So, new problem: getting a mainboard built based on the legacy sources. I hate to say it, but please please please GHI write somewhere how to do that easily based on your sourcecode.
UPDATE: If anyone have this problem, look at https://www.ghielectronics.com/community/forum/topic?id=16845&page=1#msg167085