Press Alt-R. Use Ctrl-F (and check the box for searching all files). Search for :start: (*with* the colons) and see if you have anything. If so, something there may be doing it. You can post those sections here if you want and maybe someone can tell you where the issue is. Beyond that, does this pause happen when loading and not joining any channels? Or does it happen only after you join a channel? If it's the last part, then do a search for :join: ... that will probably find a LOT of stuff, so it's best to make sure whether or not it's because of joining a channel or if it's just from starting mIRC.
