Now I've got problems

I added a comp light on top of the 3D layer and turned on use comp lights and the image falls apart, z spacing off and no alising at all! !! I checked an earlier comp (one from several months ago) and it worked fine, with the same settings. G4 D-800 OS 9.22, AE 5.5, just downloaded the newest version of 3D invg from the web 3.02 pro. Help!!! Im nervous about using the GL rendening thing as that always seems to hard crash out the system. Thanks

Jon Lewis