Hi, David
(Since this a duplicated thread, I've duplicated my trivial response..)

"I'm unable to use Raytrace (not that I've seen that it actually improves anything), because of the amount black blobs it leaves ALL over the place."

Let me guess... You've used the "square" prop (from primatives) to put your background image on to...
Never use that one (for anything). Use the "Single-sided" one instead..:-))

The square prop is "double sided", and P5 and above has problems with these (for technical reasons I could explain, but not unless you really want to know).

Just substitute the single-sided square and see if that improves matters (in FireFly)

or ... it's something else altogether..

Cheers,
Diolma

(IM/e-mail me if you want more info..)