Can't reproduce anything like that here... even at weeks of use. Granted, like I said, my computer isn't slow. I haven't run mIRC 6.3x on anything slower than what I have now (AMD64 X2 6000+ w/ 2GB DDR2 800 RAM). So it's quite possible that what you describe just isn't noticeable on this computer.
I'd suggest checking your memory usage of mIRC after that period of time, though. I run mIRC with Invision installed (and that's a pretty heavy memory-use script) at around 12MB. mIRC without Invision (just a bot with trivia, weather, dictionary) runs at 9MB. If you are getting a lot more memory use than that, then the problem may be related to something else (DLL, script, etc). It would at least help narrow your issue down.
