Yes, the latest McAfee dat file update detects mIRC as a PUP (Potentially Unwanted Program). That doesn't mean it's not good to have. Any PUP detected is something that you should delete if you didn't install it in case some virus installed it and is using it, but if you did install it, then you know it's safe (assuming you got it from here). Just go into the scan report and click on mIRC and choose Trust from the options and it won't detect it again (unless it's installed to another location later).
