Initially, you would start to descend. But at least two other factors spring to mind (there are probably others):
1. The descent would alter the angle of attack as the air started to flow slightly up relative to the wing, and the wing would then start to create lift again.
2. As you descend, your speed would increase. As that happened, the wing would create more lift. Lift is proportional to the square of IAS (might be TAS - I could never remember).
So I reckon that to maintain the zero lift condition, you would have to continually lower the nose. Presumably there is some limiting condition to this process, or else you would just end up in a vertical dive.
Isn't aerodynamics fun!
[This message has been edited by low flyer (edited 19 September 2000).]