I think it was the other way around; you got infected with some virus, and that virus installed a (modified) copy of mIRC on your PC.If mIRC, as part of the payload of a virus, is (re-)installed (in any modified and/or incomplete form) on your PC I'm sure your viral infection has not been cured effectively. First cure your infection properly, then weed out its remains, like this modified mIRC you found on your PC.
Most probably you are infected with (some version of) Trojan.IrcBounce. There has been a firm outbreak of this trojan. The trojan includes a copy of mIRC that hides as Taskmngr.exe actually being mIRC32.exe version 5.7. The Trojan uses this file to run all of its mIRC scripts, including Dll32.hlp, Dll32NT.hlp, Xvpll.hlp, Httpsearch.ini, and NT32.ini. Read more, and detailed removal instructions at
http://securityresponse.symantec.com/avcenter/venc/data/trojan.ircbounce.html. Note how this page tells you how the Norton virus scanner will remove the infection itself, but NOT the files in its payload. It will not remove mIRC or the registry setting starting mIRC! You'll have to do this yourself, by hand. Symantec's info page provides most info you neec to do that. Carefully read the section that says "To delete from the registry the value that refers to Taskmngr.exe".
You are infected with a Trojan Virus or Worm if your mIRC is secretly running at startup of windows, or suddenly sending files to strangers, or joining channels or speaking strange messages you never typed, or whatever else! Please realize that we at mIRC.com are in no way affiliated with the creators of these virusses.
Several recent virusses use mIRC and IRC to multiply themselves next to their primary distribution among Microsoft Outlook users. Well known examples of such trojans are the I LOVE YOU virus, SirCam and Klez, remember? Several virusses install mIRC somewhere on your PC and start it everytime you switch on your PC. This way you can have mIRC on your PC while you never installed itMake sure to collect lots of information and take the appropriate action. A virus infection is not something you can simply solve by deleting some files or re-installing mIRC! You need to get and use a good virus scanner and probably change your attitude towards strange files. It would be great if reading the info
on our website learned you what caused your problem, how you were involved and how you can prevent this from happening again in the future
I hope you get well soon!