Have just taken BALDRICK'S advice (ipconfig/all) and following is the output,

Windows I.P. Configuration
Host name gavin-Odb571a
Primary DNS Suffix
Node Type Unknown
I.P. Routing enabled No
WINS Proxy enabled No

Ethernet adaptor Local Area Connection
Connection -specfic DNS suffix
Description Realtek RTL8139/810x Family Fast
Ethernet NIC
Physical address 00.13.8F.F6.ED-58
Dhcp Enabled Yes
Auto Configuration enabled Yes
I.P.Address 192.168.1.100
Subnet Mask 255.255.255.0
Default Gateway 192.168.1.254
DHCP Server 192.168.1.254
DNS Servers 192.168.1 .254
Lease obtained Wed March 04 2009 8.21.50 pm
Lease expired Thurs March 05 2009 8.21.50 pm

Not knowing really anything about how all this works perhaps some one can help me to fix this.
Does this problem mean that some emails sent to me may have gone elsewhere?
Thanks
BAYBOY
PS Thanks Milkman for starting this off.