If SAFELIST is anywhere in an 005 numeric while connecting to a server, mIRC seems to think the server supports ELIST. That causes problems with /list! mIRC will send LIST <10000 rather than just LIST to a server that does not have ELIST capabilities. I'm using mIRC 6.16.

EDIT: I suppose it is also worth noting that this only occurs if the token is "SAFELIST." Any gibberish like "MOOELIST" doesn't cause the problem.