Laptop does not always recognise server

[John]

Hi,

I'm having problems with my new laptop (Dell, Ubuntu 8.04)in getting it 
to recognise my server. My old laptop (Ubuntu 6.06) does recognise the 
server in all aspects.

To be specific (on the 8.04 system):

 From a terminal window: ping server by ip address - works fine
 From a terminal window: ping server by name - works fine
(seems to suggest that DNS is recognising my server to resolve the 
addresses)

In Firefox: try to access my local home page by IP address - works fine
In Firefox: try to access my local home page by name - Address not found 
error
In Firefox: try to access my local home page by name but with my 
external URL (.co.uk instead of forcing the local intranet domain, 
.local) - works fine
In Firefox: try to address my server's CUPS pages by IP address - 
requests authentication so OK
In Firefox: try to address my server's CUPS pages by name - Address not 
found error

In OpenOffice.org: try to access a postgresql database on the server by 
name - can not resolve name


Given that all of the above tests work fine in U6.06, what do I need to 
configure on the new 8.04 laptop to achieve the same result?

Thanks in advance

John