Well the rezipping of Pugsy's cheat.zip was not the problem. I just downloaded a fresh copy of Pugsy's cheat.zip and enabled cheats for MAMEUI 0.142u2 and it still crashed while trying to load Space Invaders. So I guess whenever I play Space Invaders, I'll either have to disable cheats for MAMEUI 0.142u2 or I'll just play it on the official MAME 0.143. It must be a bug in MAMEUI 0.142u2 that causes Space Invaders to crash sometimes when cheats are enabled.