After installing the Developer Preview 3, I downloaded the update for iMovie but due to an connection error it got cancelled, and I had to redownload it from Purchases. I realized then that there was a the normal iMovie icon which worked and a phantom iMovie icon next to it which appeared to be stuck downloading. I have tried the wiggle delete, the restart dock, killall and none of them have worked so I tried deleting and redownloading the app but now the original icon is gone and there are 3 invalid copies in the launchpad. The same problem has now occurred with the iwork applications. How can I delete these invalid icons? Thanks in advance.