It appears that changing AecCore.crx in C:Program FilesAutodeskAutoCAD LT 2014 to AecCore.crx.old or similar (in order to stop it working) fixes the flickering symptoms, making the program usable again. However this will most likely break something else as this file is an object enabler. The underlying issue appears to be with the new mapping feature (which makes sense as there is a greyed out map pin next to unrecognised when the bar flickers) and that is not working properly.
We all wait now for a Service Pack or Hot Fix for this from AutoDesk. Please check out this page regularly to see if the hot fix or service has been posted. I will update my blog when it arrives to see if it fixes the issue!