Any ideas on how to fix this ? Only just started - probably caused by a Windows 10 update ?

Make sure that all your drivers (esp video) are up to date, and if that doesn't work, try reinstalling Audition. The other possibility is that this is an alternative way of reporting the .dll file error that a number of people have reported. If it's caused by this, then a C++ library may need to be reinstalled. And yes, there's a good chance that M$ is behind this...