File Error: Access Denied on FCP?

I shot my documentary on a Canon T2i. I went on FCP to upload my clips and begin editing. I am not quite sure what the preset for my capture and sequence were before I started but I swtiched computers mid-way I was editing. Everything was saved my external hard-drive and now the FCP on the computer I am using will not let me render anything. It keeps saying "File Error: Access Denied". My documentary is due tomorrow and I don't know what to do.