I just upgraded my Mac system from Leopard 10.5.8 to Snow Leopard 10.6.3. I did a clean install of Snow Leopard, so I had to reinstall all of my apps, including the Sony XDCAM EX Clip Browser (v2.6).
Now, if I have a card mounted, the Clip Browser crashes immediately on launch. If no card is mounted, Clip Browser launches, but can't detect any cards once they're mounted. I'm not using sxs cards, justSD cards, and I'm trying to read them using SanDisk reader.
I ran into this problem too. It's actually, oddly enough, the Sandisk reader. I had an older Sandisk reader and I needed a second one. The new reader kept causing the behavior EXACTLY as you described. I went back to the old reader and everything worked perfectly. Odd but there's something about the new Sandisk reader(s) that ClipBrowser doesn't like. The reader works fine otherwise.
I'd thought I'd tell you that before you pull your hair out. I would never have known this if I hadn't be happily using the older Sandisk reader for a year. At first I thought maybe it was something I updated recently but the problem went away when I switched readers.