After signing in to X@, I have attempted several times to mask my IP by using the command /mode mynick +x, and my Pirch program disconnect/closes. I have also tried using //mode $me +x and it does the same thing.
The OS I am using is Windows 7
I would think if this is a glitch with Pirch it would have been discovered by now. I don't know if Pirch has any scripting functionality but if it does, that might be causing the problem.
For now, try this instead: /raw mode yournick +x
That might get you masked even if you have a script closing your client with the usual command.
Hope that helps
P.S. I don't know if $me works in Pirch or not. You might want to consider installing mIRC so at least the help you get will be relevant to your client.
P.P.S. Pirch is another (pretty old, last updated in '98 I think) IRC client for those not aware.