That's not the code you gave us originally.

Since this is a CGI script, I'm assuming it's output is being fetched using HTTP. (HTTPS is the next most likely candidate. Consider HTTP and HTTPS interchangeable.)

href takes a URL for value. I've never heard of the "d:" URI/URL scheme either. Your URL is unsupported or malformed.

• If that's the absolute file system path to a file on the client's computer, you'd use the "file:" scheme (but that makes no sense and some browsers won't let you for security reasons).
• If that's the absolute file system path to a file on the server's machine, you'll need to construct an "http:" URL.
• If it's suppose to be a relative URL, then you need to escape the ":".

Let me know which one it is, and I'll help you further.