Tried to format Seagate GoFlex Home (set up as network backup, but no need for network anymore), it did some weird things to my system, like not being able to recognize my Admin password. Wasted all day trying to resolve, boot from another drive, safe mode, etc. Cannot change anything due to the correct Admin password not being recognized.
Finally decided to change Admin password with much trepidation (as I know I don't know enough to mess with Terminal.) Knowing that if I messed up, I would have to reformat anyways, so reBoot with command r, thought I'd try my original ssd boot drive once more, and OMG, everything came back normal! Don't know what happened, but I'm never buying another Seagate external drive again!