I just hooked up my miner after returning from training. when i first hooked it up all 3 chains were visible but then i moved the miner to a more permanent location and hooked it back up. now only one chain is appearing. i thought it might have been an issue with the 110 outlets, so i unhooked one hash board so only one board is hooked up to my PS (i use 2, one for one board and the miner, the other for 2 boards). Even after doing this only one chain is appearing.
Is there a possibility one of your power-supplies have gone bad? You can further debug this by obtaining the "Kernel log" found on the "System" tab. I would also try re-seating the cables, and test each hashboard individually (power them one at a time to determine if they are still OK -- make sure to shutdown/unplug your miner before performing any work!)
If you can provide that file, more information should be available.