Adobe and yahoo - can't read pdfs

Hi,

I have a weird one. My boss has been recieving pdf's from a local printshop for months, he opens them, checks for modifications and then faxes back hard copy changes, they make changes and resend. He uses a Yahoo mail account and they arrive as attachments.

This morning he found that he could not get the PDF's to open from the attachements. We tried saving them and then opening, but no joy. He tried updating to the latest adobe (8). Still no joy. The message that comes up mentions possible corrupt pdf's - but if that the case then...........WHY - if he sends them to his outlook email address can he can open them just fine there! Also if he sends them to his wife's email and she opens them on HER computer - no problemms! - What is going on?? - He wants to maintain use of the Yahoo account for various reasons.

Previous pdf's (stored in yahoo email inbox) that he used to be able to open he can no longer open too.

Any ideas?

Thanks:confused