My problem turned out to be a nasty piece of spyware which Norton couldn't see but I downloaded spybot and it cleared it up nicely.

It almost certainly is a Spyware problem. I have had exactly the same problem. Even though McAfee reported my machines as free from spyware, when I downloaded Spybot, it found 30 + infections. When I...

Might be a stupid question but have you actually set up shares on computer B ?

If not try:
On Computer B
Click My Computer
Right click on the C drive
Click properties
Click Sharing...

I tried your suggestions but the result was exactly the same. The problem has now been resolved and turned out to be a spyware\adware issue. I have been using McAfee Internet Security package to...

Thanks for the info. I will give it a go and let you know.

My old multi-sytem network had no problems using ICS to connect. Since changing to Windows XP Pro on all systems on my LAN and also switching to broadband I have hit a problem.

The main machine...