Problems with CSV file uploads not being allowed

[eluser]Nathan Pitman (Nine Four)[/eluser]
I've just migrated a small app I wrote from one environment to another and I've run into a weird issue with MIME types and the file upload class. I'm uploading a CSV file through a web form and where previously this worked on the new host using the same reference CSV file I get the error:

Code:

The filetype you are attempting to upload is not allowed.
[file_type] => text/x-lisp ) )

I've tried adding text/x-lisp to the application mimes.php CSV array but that makes no odds. I can't even seem to find a clean reference to this mime type online. This occurs both in FF and Chrome so I'm not convinced that it's a browser issue. This is a Smart Machine at Joyent that the app is running on.