Live doesn't automatically keep a back up of a song, and I didn't automatically think of doing that. Fortunately I started the song in Logic, so it didn't kill days worth of work, just hours.
I'm on a mac, using a dual Gig G4 machine, and a powerbook 800mhz, the song was at about 80% CPU with Pluggo plugs, native Live plugs, Native instruments (maybe, don't remember), Buzzer, PSP Vintage Warmer on the output.