DNS failure

Hi Folks,

I have 2 computers sharing the internet connection.

Computer A has the internet connection and has no problems pinging,
tracerting or accessing www.google.com on the internet

Computer B cannot access anything
'Page cannot be displayed' on the internet
Pinging www.google.com
Destination net unreachable
tracert www.google.com
Unknown Host

nslookup
default server: unknown
address : 81.23.199.132(preferred DNS server)

Does anyone have any ideas on how to fix this?

Regards,

Johnny5