Most good virus programs will not tell you there is a problem with mIRC, or will just notify you that it's installed and let you decide what to do with it. mIRC *can* be a problem because some people do make trojans that use it, and some make it run hidden so that it does things without you even knowing it's being used. However, if you scan your computer regularly and keep track of what programs are running on your computer, you should have no problems with it. Those are really just warning in case you do not know it is installed.
Your options are:
1) Contact the company that puts out the virus scanner and ask them to remove mIRC from their automatic detection/removal. They may or may not do that, but you can try.
2) Use something else. There are many good antivirus programs out there that have no problems with mIRC, including free ones such as
AVG.
