I just upgraded to Snow Leopard on our Mac, and when I tried to use Opera, the icon just kept jumping up and down in the dock but didn't open. I uninstalled it, and then tried to reinstall it, but when I try to open the download, the computer doesn't know how to open it. Anyone else had this problem?

I'm also having difficulty when I try to install Lotus Symphony. It says it's installed successfully, but then when I try to open it, it says it's damaged or parts are missing. Anyone had a problem like that one?