My downstairs toilet will over flow after we empty the bath tub, or after the washing mashine goes to the rinse cycle during full loads. My neighbors aren't experiencing this problem so I believe it may be specific to my home. Keep in mind that it only occurs when we drain large amounts of water from the bath tub or washing mashine. Out side of calling in the plumber what are some suggestions to fix this?

It seems to me as if you have a main clog and it has not completely closed up, but will. The choice seems clear to me. Either keep cleaning the floor or have the clog addressed by a sewer machine. If the clog comes back or if the machine retrieves roots then have them camera the line. Tell them you want the video tape.