I originally thought it was just startx, but now I've discovered ALL commands are "not found" for any user except root... I obviously haven't checked the path for every single one, but the path for 'startx' is fine.
Basic commands such as ls, echo, cd, etc. all still work, just not ones I've had to install like startx, nano, google-chrome, etc.
This happened after installing Vidalia, with the dependencies libevent, GeoIP, tor, and vidalia. Vidalia ran once, but did not run again, and upon reboot all was gone... was this a virus?? (all were from Slackbuilds)