Hello everyone, I use both Preview in Lion and acrobat X to read and comment the papers in PDF. Preview is much greater in smooth scrolling and running speed. But I met a serious problem when highlighted texts. For example, I selected one sentence in preview and highlight it with pure yellow color. Then I opened the same file with preview, or on another PC with adobe reader, and made some highlights. I did it several times everyday. Then I suddenly noticed the highlight color changed little by little! As I said, I used pure yellow originally and made some changes with another program. When I open it with preview again, the gold yellow color was likely mixed with a little brown and went lighter. When I repeated these operations again and again, the yellow went to be very light brown until can be hardly seen. Now though I prefer preview very much, I have to use acrobat only to make sure the highlights can be shown properly everywhere. I am not sure if I describe the problem clearly with my poor English. But does anyone know what is wrong with these two programs? Is there any program setting I missed? Any help will be appreciated!