Auntie Val , Physics behavior and Solid behavior aren't the same thing
If you are using solid behavior , I believe there's a way to disable it
Yep ( Taken from manual )
Enable or disable Solid for this object. If disabled, the object no longer acts as if it is solid, and objects will be able to pass through it. Be careful not to trap objects by enabling the solid again when an
object is overlapping it; see Avoid crushing/trapping objects with Solids.