Thank you for your post.
Yes, a problem has been reported and confirmed with Safari 5.0. If the PDF file is small enough to render in Mail, it has a black background. If the PDF file is large, the file icon is surrounded by a large black border with a close icon similar to a web object pasted into a mail. This problem also exists with all other applications using the attachment operation.
See another thread on this forum at:
There is also a thread on the Apple Discussions board at:
This does not affect the integrity of the attached file.
Apple has released a Support note:
They are aware of the issue, so hopefully there will be patches for both Safari and Mac OS X 10.6.4.