Replying to Final cut transitions = fail

ok, working with 960p footy shot on a GoPro HD. i have a macbook pro and i'm using final cut pro 6. all i'm trying to do is make simple title overlays using the text tool within FCP and a few crossfades and dip to black transitions here and there, nothing really technical at all. i've done this sorta stuff before plenty of times with no issues, but for some reason when i go to export to quicktime, anywhere i'm using a title or a transition between clips, it renders out either really pixelated (aka quarter-inch sized blocks of color), the stutters, or the video just greenscreens for the duration of the transition. anyone have any ideas what's going on here? the gopro is gonna be almost useless if i can't even edit video.

p.s. please do not suggest using imovie. i hate it with a fiery passion, and plan to start playing around with more advanced features of FCP that are not available in iMovie. i never really had issues like this using premiere on my PC, so what gives?