Please see this thread. Any channels or servers that use only code page support and not UTF8 support will have issues until they start supporting UTF8. You will have to stick to 6.35 until support for UTF8 is added to those channels and/or servers. The main reason to upgrade to mIRC 7.1 is for unicode support and if you aren't going to use it, there's not much reason to upgrade anyhow.

Invision Support
#Invision on