Shoutbox

I'm not sure if there was a post about this already or not, but everytime someone tries to send me a file, or I try to send someone else a file, it says "This file has been blocked because it is potentially unsafe." I'm not sure why though, I set my Norton Antivirus to allow Messenger to accept files, and I've also set Messenger to auto accept files. I can't accept anything in MSN Messenger...