Hey Ryan,
I have the exact same problem and I cannot seem to fix it. Have you had any luck with it? It seems to occur for me after I have exported the sequence through Compressor once, and if I try it again, I get the message “File error: a file of this name already exists” and you know the rest. Both your problems are related because the only time I get the immediate failure in Compressor 2 is when I get the error message in Final Cut 5. Let me know if anything comes up.
Thanks
Ben