This happened in 6.15 and maybe 6.14 as well. I'm using 6.16 now. I did a fresh OS install. Installed MIRC 6.16. Set dcc options to auto-get and then check the mirc.ini file. It's still set to warn=on. If I change it in the .ini file to warn=off, and then go back into the program and select auto-get again, it'll set warn=on in the .ini file.