I have had the exact same type of situation, and went around the neighbors homes and saw very simular effects on different types of things.
POCO phase went out (1 of 3) and what would seem like a normal power outage got wierd. From I assume is the induction of current from the other 2 phases on an open line. Having talked to the line crew already, the whole phase was open due to a HV fuse that they were waiting for. (~3 hours) Having shut off my main at my house, I went to the other homes on the block to tell them to do the same for a little while until this blew over.
The induced voltage to the open phase over about a mile was enough to create ~74/136 through the transformer in my back yard. Although not really usable for most things like incandesant lighting, certain electronics acted very differently. Flashing screens of TV's, flouro lights, squealing cordless phone bases. Of the dozen or so neighbors I talked to they all had something wierd going on. Reguardless of what anyone else says - it can't be good. Maybe not as damaging as an over-voltage, but a lower voltage producing a partially usable current in less robust electronic items.....
IMO if they had grounded the conductor - it would have seemed less wierd. They were comfortable with not doing so - but the effects were freaking me out....
