Unable to edit original post, so I'll continue here. I've searched for more information on this, the best I can come up with is that i need to install the nVidia GeForce drivers to resolve the issue. Is it likely that this will provide a solution: ie can one of the members with more insight into the differences between 6.7.1 and 7.2.0 be able to verify that it is likely a driver problem?

I note also that the driver install also necessitates re-compiling the kernel - is this really practical or should I just go back to 6.7.1?