Thanks for all the help and suggestions. I ended up connecting the unti to the network via cable and everything worked perfect. Only thing is now I have a really ugly cable running across the floor in the living room!
No problems with the wired connection so I am a little on the confused side now but I do have it working now so I guess I will just forget about it for a while!
Thanks again
Jamie
OK, so it is definitely something on the wireless side of things ....
* check that the router IP address is entered correctly on the SB.
* check that the SSID (your wireless network passphrase) is correctly entered on the SB (including any blanks).
* if you have setup your router to only let specific MAC addresses connect to it, check that the specified SB MAC address on the router is entered correctly.
If these things are correct, it should connect OK. If it doesn't, check the settings on your other (working) SB's for any differences. If there are none, reset non-connecting SB to defaults and set it up from scratch. It is most unlikely that there is any hardware problem, it will be an incorrect/dropped setting on the router or SB.