LO2016 crashes when opening a file created in LO2015

I am using Windows 10 with an AMD Radeon graphics processor (0 x 6750) which I have checked is fully up to date. I created large files using SU2015 and LO2015. Then I updated to SU2016 and made many changes to my SU model. Now I am stuck because I can’t import the SU2016 into LO2015 and LO2016 crashes. I tried running LO2016 “as administrator” but that didn’t help.

What can I do?