[asheshouse]

Use the ActorsLite tool in the basic map tools pack. This is the act.jar routine mentioned above.
extract the actors file then create a new one using a blank outwings.txt component.

This new actors should work ok.
If it does then you can use the iniital extracted outwings.txt to gradually add the bridges back in until by trial and error you find the one which does not work. The previous comment about needing a section of road or rail between two bridges is correct.

Ashe