The Netbios was set to default on both so I clicked enable, Checked everything else. What I found was the IP for comp A had somehow changed from XXXXX.100 to xxxx.115. I don't know how. The IPs were 100 and 101, Allways have been. Anyway everything works now, All drives etc can be accessed from everywhere, Brilliant.
Thanks very much for your help.
I have printed your replys and will put them in my 'Modem' folder for next time, Because there will be a next time.
bothered.