Printing issues with preview on snow leopard

I have a PDF that I scanned in myself and the first time I printed it it printed just the way it was supposed to. The next time I opened up the file in preview it looked normal on my screen but when I went to print it the output in the printer had the colors inverted. I have tried printing from preview and adobe acrobat and it printed the same the blacks came out white and the whites came out black. So I tried printing it from a windows computer and the file printed as it should, the colors were normal not inverted.

Does anyone know how to fix this? It doesn't happen to every PDF just a few that I have.

Thanks