Vista - windows live messenger - cannot sign in for certain account

I try to install Windows Live Messenger 8.1 but it says I have the newer
version in my Win XP Home SP2. That ok. The strange is I cannot sign in (say
account AA) as it gives an error 8100030d. but I can sign in using another
computer.

I set up another account say BB (on the same computer as account AA) and I
can sign into the Windows Live Messenger.

At www.hotmail.com and I can log (account AA) into my email on both pc's. So
whats seems to be the problem for been unable to sign in using account AA?
Very strange isn't it? Anyone care to comments//

Goole for error 8100030d, from this website,
http://messenger-support.spaces.live...3F!13937.entry

and quote:-Delete Windows Live Contacts Folders in Windows Live Messenger:

In Windows XP, go to C:\Documents and Settings\<Windows logon name>\Local
Settings\Application Data\Microsoft)

Any idea what is the exact name of the folder that I must delete? Appreciate
your response, and thanks