MSNbot - robots.txt

Yep, I've always had forum/attachment.php disallowed in my robots.txt, yet every single time I see MSNbot on my site, it's hung up on the same attachment getting a no permission error (no attachments for guests on my board). Why does MSN simply ignore my robots.txt directives? Yesterday, MSN showed 6 hits in my bots log, and that was all on attachment.php looking at an error message.

Is there any hope for MSN?

Eek, wrong forum! That's what I get for posting before I have my coffee.