I used this answer: Install xCode 3.2.3 w/ iPhone SDK 4, get "Base SDK missing", can't see other SDKs and it doesn't work. I still have "Base SDK Missing" and I can only choose simulators to compile for. I'm ready to device test but there's no iPhone in the Active Executable list.
I just updated to the newest 4.2 and 3.2.5 XCode