@Robert: Thanks for acknowledging this problem. This is unusual these days and much appreciated!
I just wanted to pitch in my two pennies that I see this also and reliably so, but on a fairly recent and not all too heavily loaded Win7 Pro Acer M5810 system (i5, 2.67 GHz, 8GB RAM).
I can reliably correct this behavior by downgrading to BoxCryptor 1.3.0.0 and equally reliably make it reappear by upgrading to 1.3.0.1.
-- Ingmar