Full Reboot - Paranoia. Friend Computer has finally decided to just kill everyone in Alpha Compmex and start from scratch. Its the only way to root out those subversive elements once and for all. The PCs are somehow accidentally informed of this, even though it's a secret that not even the ultraviolets are supposed to know. Now they have to deal with it. Either stop it (Humanists, Romantics, Phreaks), take down the computer first (PURGE, Death Leopard), help it along (Servants of Cthulhu), find a way to survive and re-insinuate themselves into the rebuilt world (Psion, Illuminati), or Kool-Aid time (FCCCP)
EDIT: Or escape outside (Sierria Club)