Do note, this is an mIRC bug report forum - to report bugs that occur inside mIRC. This would have been more appropriately posted in 'General Discussion', or one of the 'Support' boards.
I strongly suggest you scan your computer with 2-3 virus/trojan scanners. Lots of resources can be found in
this thread. Make sure you also read all the info there so you can stay safe in the future.
G'luck!
Regards,