Safari does not display pdf's properly...

MacMini 2010, OS 10.6.8, Safari 5.1.10

Safari is not displaying pdf's properly that I can see perfectly in Chrome and Firefox...I get this weird pattern of black shapes....

Works OK on my laptop OS 10.7.5, Safari 6.1.1 (after I allow it to access Adobe Reader...)

Any ideas? The pdfs are printed/made from MS word docs. The header is a placed image. Also attaching screen shot from FF.

Thanks