I posted this over on the steam forum, but I thought I should also post it here as well.

I've had NotEye crash twice on me when I gained multiple achievements at once. I was using the Tiled mode with size 32 tiles and the block mini-map option.

The game shows the dialog for the first achievement and then crashes to the red NotEye crash screen. Steam pops up both achievements with it's own message pop ups. The only way to resume is to fall back to ASCII mode. Afterward, the game is redrawn in ASCII and paused until I hit the space bar, which then brings up the dialog for the second achievement in the game window after resuming. I suspect the "pause" is the game waiting for me to dismiss the dialog for the first achievement but it is not redrawn after switching to ASCII mode.

How to reproduce:
Trigger multiple achievement awards at the same time while playing in Tiled mode. In case it is specific achievements the two times this occured I was awarded Well-Known Demi-urge + Achiever, and Scorer + Consistent Believer.