Two errors encountered after using Adobe Professional 7.0 on Mac Pro

I've encountered "After effects error: create 720 image buffer" when I used Adobe Professional 7.0 on a Mac Pro with 1 GB of memory. I did not encounter only one error but two. The second error I encountered was: "After Effects error: Quick time export failed-out of memory (-108).” Why does this occur? I'm sure that there is an enough memory in my unit. Please, please help me fix this. I don't know what to do. Thank you.
