Well, for a start I don't recommend using a task killer. At all. It's a very hotly debated subject in the world of android, but you really shouldn't need one. (Android is designed to keep your RAM full of apps, and a task killer just screws everything up). They are only really good for dealing with misbehaving apps, in which case you're probably better off uninstalling the app in question.
I don't really know about the other two. I would normally recommend redownloading and reflashing (or updating to RC1 in this case), in case of a corrupt download/install. It's always possible your task killer is to blame too.