I did mention I was having an issue with my wireless network topology and channels. I was having to use the Automatic channel setting which meant my older UFO shaped Airport Extreme decided channel 13 was best.
Well first problem I had was my HP TC1100 Tablet PC did not like channel 13 and refused to connect and co-operate.
So I knew I had to change the channel.
Well I changed the channel from Automatic (13) to channel 6 and guess what? Yes it all works fine now!
Bizarre!