OK on OS X - you might be getting hit with the specific file encoding, often there are magic comments at the top of the file or the file itself is set to an encoding. You can alter your file encoding on Mac OS X like so:
iconv -f ISO-8859-1 -t UTF-8 File.txt > File.txt.utf8
And for a bunch of files:
find /path/to/Workspace -name \*.txt -type f | \
(while read file; do
iconv -f ISO-8859-1 -t UTF-8 "$file" > "${file%.txt}.utf8";
done);
This will convert all txt files, change *.txt to get different file types.