While mining my action became slow and computer suddenly crashed. Had to shut power off to shut down. Restarted, returned to game seemed fine. Then encountered mini cave with lava. Water didn't affect, gravel wouldn't drop, broken blocks didn't drop item, temporarily got stuck in area. Escaped to surface. Built rail path. Found gaping hole in middle of town. Walked in, thinking it was image not loading, fell in hole, floated down into 'void' but didn't die, instead landed back at hole edge minus level but not items. Computer crashed again. Restart: hole is still there. Left biome, everything else seemed normal, have not played since issue May 24th.