It may be a corrupt file - go to
http://www.tacktech.com/display.cfm?ttid=257 and download Winsockfix.exe ... there are loads of sites with this file, so if you can't get it there, just type Winsockfix.exe into google and search. It repairs the problem and allows you to logon again. Just run it, it repairs the problem and then reboots the pc. THEN do what I suggested in post number 10, above. Good luck