Vista and PDF's

I figure with the ultra-cool, highly sophisticated readership I have all the problems of the world can be fixed. Or the two people who actually read my blob (not a typo), Tony and Richard, know people who can fix this problem.

On our new site we're having some problems with downloads. Here's how it goes down:

Someone goes to this page on our site.

• Three out of the four pdf's download no problem. Lesson one corrupts on the way down.
  
• We've been able to track down that this might well be a vista problem.
  

What we've done to troubleshoot:

• Re-saved the pdf backward compatible to acrobat v.5
  
• Renamed the pdf
  
• Emailed the pdf to the person who couldn't download it, they were able to open the email.
  

This is becoming one of those increasingly negative problems. Just happens that other than homepages, this is our most visited page on the site.

P.S. Same seems to be happening with some audio downloads. Two work one doesn't. I think the problem is related, since it also appears to be a Vista problem.