Game and steam crashes when finding players for Co-Op

Whenever I try to start a public mission the game starts the searching for teammates process but before it can find a full team the steam client crashes in the background without any error message, which in turn freezes the game until eventually that crashes too without any error message.

I have tried many solutions including:

Running in a window
Vsync on and off
Validating files
Disabling Killer network manager
Lowering all of the graphics options to minimum
clearing steams appcache

None of these attempts changed anything and now I am getting very frustrated since playing the missions Co-Op was the sole reason I bought this game.

Anyone else got any suggestions as to how I might fix this?

Just for the sake of completeness here are my system specs:

Win7 64bit
Core i5 3570
8 gigs of DDR3 RAM
Nvidea GTX 660

Which all meet the recommended requirements.

As an update I have also now reinstalled steam to no avail.

I managed to finally get a crash log to appear and fixed the issue.

If anyone else is having this problem I first had to uninstall each of the Nvidia components ie. physx, driver, Hd audio etc. restarting the system after uninstalling each one.

Then i reinstalled the driver, used custom install, deselected the 3D vision stuff and told it to do a clean install. After a final system restart it seems the problem is fixed.

Hope this helps