I'm trouble-shooting a new G5 iMac with a built-in iSight camera. Whenever you launch PhotoBooth or iChat, they report that the camera is "in use by another application." It isn't -- and I can't find any process in the Activity Monitor which looks like it might be latching onto the camera. The iMac is almost new. The iSight worked correctly for a while. I've tried creating a virgin user, but this account reports the same issue. Any suggestions?