Toast 8 Region Code Error

Videos DVD's I burn using Toast 8 will not play back on regular DVD players (I have 2 Sony models) and cause a region code error.

DVD's I've burned using iDVD work fine. The DVD will also playback on the iMac using DVD Player.

I've even tried putting North American DVD's in the iMac to ensure the DVD drive is set to the correct region.

Any ideas what this could be?

iMac 20" Intel Core Duo 2.1 GHz, 1 GB RAM Mac OS X (10.4.7) PowerBook Titanium G4 400 MHz, 768 MB RAM