ibook G4 internal bluetooth - broken?


I've just bought a new Apple wireless keyboard for my ibook G4(6 months old), running Tiger with the latest updates.
Previously, I have used the internal bluetooth card which I had installed upon purchase of my ibook to successfully sync with my phone with no problems at all.

Following the instructions supplied with the keyboard, I installed the bluetooth driver supplied on the CD (Apple Bluetooth Firmware Update 1.1), followed by the MacOSX bluetooth update (version 1.3).
That's when things took a turn for the worse - after the Bluetooth firmware upgrade, I could no longer see my Bluetooth connection - the Bluetooth logo appears in the menu bar, but it has a zig-zag line through it with only one menu option - "Bluetooth - Not available". Not good!

Since then, I've tried running the hardware diagnosis CD which came with my ibook but it can find no trace of the bluetooth module, neither can the standard macos hardware listing.
I've also tried a later version of Apple bluetooth firmware (version 1.2), which runs right through but doesn't return a successful message at installation completion.

Do you have any suggestions of any other updates / utilities I could try to get my bluetooth working again?