Bah, I've had SixtyForce for well over a year, since back when it was called mac1964. It's nothing new. Zelda 64 and many newer ROMs don't work at all. In fact, the only game I've gotten to play well is Super Mario 64.
Sheesh, it's about time that guy updated his program. I had given up on it months ago because of his lack of updates. I think I deleted my old ROMs as well. No loss, though, because I only used it for the "coolness" factor since the games run SOOOO much better on the actual console.