This is a bit of a random failure, which may make it hard to track down, but I've gotten a Slick-C stack on a push-ref three times so far since using the beta's. If I do the push-ref again on the same symbol, it works. I'm using VIM emulation and using Ctrl+/ to do the push-ref. I'll attach a screen image of the windows that pop up.
Edit: I just had it happen again