To check the mirror's MD5 would require downloading the entire program, since merely having some kind of MD5 query would mean that it could easily be faked. I don't think mirrors would appreciate their traffic being doubled, nor would mIRC's hosters whose traffic would go up by about 30x. A simple solution would be just to verify them once per day or something like that. At least then we wouldn't be in the position we are now where this thread has been up for around 36 hours and the mirror is still up. Who knows how many people have been infected in that time?
