I’ve never had a problem with PS on the mac. How are you trying to open the jpgs? I usually do it either from a finder window by right clicking (that’s control click if you have a mighty mouse) and choosing open with adobe photoshop or, if I am already in PS then Command + O, or from the toolbar-file-open.
It might turn out to be the easiest option, but I would check that you can open the images with Preview first. Either open Preview and try and open the images from there or right click on the image and ‘open with’ Preview.