please although i am in one room i cant join any channels every time i am trying to join other channels tell me that :
you have joined many channels ( too many channels are open )
That doesn't look like a default server-side message. Try doing the /!remote off, then /!join channel.
You know it isn't a mIRC issue when you can try another network and join more than 1 channel.
You know it isn't a mIRC issue when you go on java applet on the same network and can join more than 1 channel.
Matter fact, scroll in your status window and look for an all-capital maxchannels=<Number>. And tell us the number. If it is 1, then it isn't a mIRC problem.