OK I got the workaround...have tried many times on my another computer
1. Uninstall MSN Messenger 6.1, and install 6.2. Reboot isn't required.
2. Don't try to sign in yet!
3. Open your registry editor (regedit), locate HKEY_CURRENT_USER\Software\Microsoft\MSNMessenger
4. Export the whole PerPassportSettings to a file. (That is, back it up)
5. Delete the whole PerPassportSettings sub-directory.
6. You should be able to sign in successfully now. After you sign in, just sign out immediately.
(You need to perform signing in/out with every .net messenger passport acccount you have)
7. Restore your exported registry file - just locate the file and double click it. You will be prompted and click Yes, OK.
8. The
revisedcookie bad cookie is crumbled
(OK, joke, cookish, don't be angry please...
)