had a little play with the PC this morning and after I did a restart 3 programs popped up on the windows firewall list that I didn't recognise so I did a bit of digging. 2 of them didn't even exist on a google search so they got deleted straight away and the other was a bit more sinister.

It had called itself Isass.exe, but the I looks like an l in the windows font so at a first glance it looks like the windows system file lsass.exe.

After deleting this I could connect to the net via my router so I updated the virus software and it found a total of 7 viruses on the PC!! A quick clean up and all is well now

Thanks everyone for your suggestions and help