Hi all,
I’ve been having a similar problem with FCP7 – “File Error: Access Denied” on render. This is typical of a read/write permissions problem. But when I changed the read/write permissions, no effect initially. However, when I changed the capture/render scratch in System Settings to another hard drive, and then changed it back again it worked. Bizarre, but i’m rendering again.
The most likely explanation I can offer is that FCP hadn’t realised that the read/write permissions had changed. FCP does occasionally come up with some weird minor glitches like this, as does Snow Leopard (like applying read only permissions to drives without your knowledge).
I recommend changing your render scratch drive, rendering a couple of clips, then changing it back again.