I'm a bit stuck on something and need help!

I have an RGB module attached to a leostick which is slaved to an arduino duemilanove on an i2c bus.
I'm having a few issues with this setup, namely :
1. Once the Duemilanove (master) joins the bus, the RGB Module seems no longer to respond. (it works fine when not attached, or when I comment out wire.begin() on the master).
2. While I can send messages from Master to slave, I can't seem to request and receive data from the slave leostick.
3. The Piezo on the Leonardo makes an audible hum (sounds like 9600Hz) when the I2c is running.

I'm new to i2c and the RGB module, so it could be something simple, but I'm tearing my hair out here...
My sketches are attached...
Any ideas?

cheers,
Richard Allen
Melb, Australia