just in case this may avoid people losing time in this period of windows 10 reinstalls:
Exporting a mix down if you have not validated the licences of all your plugins may freeze cubase at the very beginning of the export up to the point that the process must be killed from the task manager.
This happened to me with Pianoteq 5 plugin that was playing two notes in a large project I loaded to test after a windows 10 reinstall. I forgot to validate its licence and It took me half a day to spot out why everything was playing OK but exports were immediately freezing cubase. This may occur with other plugins too and happened with both Cubase 7.5 and Cubase 8
PS: still have to deal with very frequent DCOM errors with synsopos and another issue that occured less frequently which states that I have no more codec available when exporting in mp3 and invinting me to visit a shop … next time I will write donw the exact error