Can't sign-in from window messenger

Through Add/remove, I have uninstalled Outlook Express
and Window messenger and after sometime I reinstalled
them again. In between I can't rememeber what I have done
on the registry. After reinstalled, window messenger 5.0
can no longer auto sign-in.
This XP pro computer is client using MS ICS to access
internet. It can browse around the internet and the other
workgroup computers but funny that in its Network place,
the internet Gateway icon showed "disable". I remember I
have mistakenly started firewall on this client computer
where I could see additional adapters installed. It is
something related with IPV6 or Tomedo??? I eventually
removed these additional adapters and IVP6 while I can't
remember what steps I have done.
Are all these related to the problem with window
messenger 5.0's auto sign-in? It pops up in tray while I
activate Outlook express. Even I tried to click my email
name to manually sign-in, it just does not connect.
Please advise how I can make it work again. Thank you.