Launcher.exe closing after 5 seconds, no error message

[unreasonable]

So far I have:

Reinstalled CoD.

Verified file integrity thingie.

Checked I am up to date with patch (I am)

Reinstalled DX

Reinstalled Net.4

Rolled back to 260 nvidea drivers from most recent set

Turned off Avast firewall.

No dice. I get the a/c and gunsight logo then after 5 seconds the launcher error window. If I close the error window (but not exit the program) I get the Ubi movie and then the epi warning, and I can get to the menus, but any attempt to alter settings will not work. If I try to load a mission I am returned to the previous menu page and the error message reappears. Closing this exits CoD altogether.

I have pet techno-geek who is going to come and check out my setup but he is not available until 13th April: if he comes up with a solution I will be sure to share!

All a bit of a shame as I am enjoying my training flights on my other inferior PC.

Specs: Win 7 64bit, Intel Core i7 CPU 860@ 2.8GHz, 8.00GB RAM, nvidea GTX 470