I'm not sure about the problem (at a guess, it's the forward slashes instead of backslashes in the Windows pathname), but I do have a formatting tip. To format code as code, surround it by blank lines, and then indent each line by two spaces. This will result in code being rendered in a monospaced font with whitespace (including returns) preserved.
open-output-file: cannot open output file: "C:/tmp/shashd39M2tCqX6"
It looks like the official arc2 distribution is being used here, which isn't smart about pathnames, so something in arc.arc, ac.scm, or something like that is just blindly using /s. If the Anarki is being used, then this bug should have been fixed. But as I said, I have a Mac, so I'm really just guessing here.
