And right after I resume the game from paused, the fozen zombies all die and new ones swarm me. Not the only glitch I've seen, though, and it really needs a save, not just checkpoints for that playthrough.
I got to wave 27, then the screen glitched and the zombies who were on it, and the cash awards just stayed there, not moving, but I could still move around and fix the car, and even shoot the flesh off the frozen zombies. No more zombies could come though, and I couldn't get the cash to buy the last gun to get the perfect achievement. Oh well.
 "Dude and Zombies"){kind=icon}
 "Heir"){kind=icon}