Condensed or overlapping letters in pdf

[EMPM]

When making a pdf in Acobat 7 Pro we see a properly created pdf when viewed on our Macs. After emailing the pdf, a minority of our windows customers see a document where some of the words are condensed to a single spot or just badly over lapping each other. I tried reading it on our windows machine and I was able to recreate the problem using Acobat 5. The problem does not occur when using the latest reader however. The easy thing to do is tell everyone to upgrade but this isn't always practical. The .pdf's affected are not necessarily created by the same Mac and where I would send a document that reads properly, someone else in the firm will send a screwed up pdf and then vis a versa. I have consulted with Adobe but when I sent them an affected pdf they saw no problem on their end using Reader 4 to 7. This is truly odd. Can someone help.