I was trying to download some free compressing applications for Mac, from NCH site, Win Zip 3.0 for mac etc, found the sites and click on the download table, then the screen turns into black immediately. As for y tube, it seems only swf file can be viewed, others just a black placeholder, this has been happening for about 10 months. (While I used the right click to compress the files, it produced a zip file without any compressing at all, the size of fill didn't change at all. that's why I am trying to download a compressing application.) Many THanks for your help. jane