Default [Q] 2 questions - security pin and memory compatiability

My Nook HD+ has an annoying issue - often I have it lock to the security screen where you enter a pin and it will start to unlock and then immediately lock itself. Has there been a fix for this yet? Using CM 10.2.1-ovation

2nd question - Has anyone been able to verify that a Samsung 64GB EVO microSD works with the HD+? I found an outstanding deal on these class 10 cards but don't want to buy them if they do not work.

Thank you in advance!