These script errors could either be caused by MSN Today / WLM Today or by the advertising banner.
To disable 'WLM Today' in Windows Live Messenger,
go to 'Tools' -> 'Options...' -> 'General' tab -> untick 'Show Windows Live Today after signing in to Messenger'
Also check your hosts file again and see if the line you added ("127.0.0.1 rad.msn.com") is still in there.
Disable Script Debugging in IE:
Open Control Panel -> 'Internet Options' -> 'Advanced' tab ->
check 'Disable Script Debugging (Internet Explorer)'
check 'Disable Script Debugging (Others)'
uncheck 'Display a notification about every script error'
If that didn't fix it, remove the advertisement banner at the bottom of Windows Live Messenger.
Use the
Mess Patch and select 'Remove Advertisement Banner'
Other threads about this issue:
Internet Explorer Script Error when MSN loads
script error when signing in
Workarrownd for the Ad's Problem
i keep getting this error