I have both the Apple Keyboard and Mouse. For some reason my mouse is always detected however in both bootcamp and OSX my keyboard takes a bit of coercing to be able to be seen. Any reason as to why?
Is this just after turning the keyboard on? I generally find it to be the other way around in OSX (I don't have Boot Camp). If it becomes a problem, I'd think about buying higher quality batteries for it. These devices are quite dependent on good quality power.
In your title, you say "Bluetooth keyboard", I thought you couldn't use perihiplas such as BT mouse and keyboard, Apple USB Modem etc., running windows on a mac...