Unable to connect to Host - COD 4 - XBOX Live.

[littlers5]

Hey, Thanks for looking, welcome all willing helpers to this thread.

I have a problem with my xbox live at this current moment.
I am using The BElkin F5D 8233 router and it works perfectly when just finding a match on call of duty 4, and all the rest of my games ie, Halo 3 etc.
But my problem is, when i am invited to a party, call of duty states 'Unable to connect to Host', when i invite people to my party, they say Call of duty states ' Unable To connect to host'.

I Have tried port forwarding using the ports TCP 28960, and,
UPD 28960
However it says my IP LAN is invalid, This makes no sence to me at all as the Private IP entered, is your external ip, correct?
So Mine would be 192.168.0...... and i enter that digit into the box provided.
Done. Still No Luck.

Any Tips or ideas very welcome as i become more and more fustrated by the day.

Thanks Very Much.