Could really use some help...again..

The round plug is keyed so it shouldnt be able to plug in any other way unless the key is damaged.
It does sound like your wiring is crossed somehow but it should be evident if someone has been donkeying around with it. Ground problems can cause weird stuff to happen, especially in lighting circuits. Bulbs can backfeed ground and cause weird issues. Run that ground and rule it out. (or hopefully it fixes it)