I'll add another.. if you get this error every time you connect to a server then also check if you have the latest McAfee installed, there is a 'new' option which by default blocks port 25 and all IRC ports.. yeah, did cost me only about 1 week to figure this out..
* Open Virusscan console (rightclick icon in systray and select virusscan console)
* Open Acces Protection
* Uncheck Prevent IRC communication

So there are propably more antivirus programs which has this new feature.. mad

I owe you the biggest Thank You in the world. I've had this Error for a long time and tried many many solutions. This was it! Simple and quick. I hope others try it and I hope it fixes everything.