Rekordbox "not responding"

I've just taken out the monthly subscription and upgraded to 4.2.1 and I get the windows hour glass (round circle thing as it's win10) and "not responding" when I try to navigate the folders on my external hand drive within Rekordbox. It does seem to come back to life, but it's going to be somewhat heart stopping at my next gig.

In case it helps:

HP Amd A8-4500M 1.90GHz laptop
8GB ram
DDJ SX (not connected at the moment)
Windows 10 fully up to date 64 bit

Any ideas?

Please let me know if I need to provide any more information