When I took AP, it was the first time they had the virtual microscopy section. My computer, and several others crashed during that session (which is why they allotted extra time per question). When it happened, I went to wiggle a wire, and was told that if I did that again, that my exam would be revoked!! So, my advice, is that if your computer freezes, YOU freeze as well.
I took the dermpath boards last week, and it was the first year that they had virtual microscopy as well. No crashes for me at least...it was faster and smoother than when I took the AP boards, so hopefully they've worked out some kinks.