Its possible that something caused mIRC's identd socket to become stale/dead/i cant think of the term right now.
You can do 2 things. Kill the listening socket using a program like
TCPView for Win9x/NT/2K/XP, or restart your computer. This should free up the socket so mIRC can use it again.
If something else starts using it again even after you reboot, then I recommend auditing the programs you have installed/running on your sustem. There are other programs at
Sysinternals that should help you with this.
- Raccoon