What in the world is wrong? I connect to a server, it lets me, then I join my own channel, it lets me, then I try to set Topic, and or anything else except the away command, and it comes back in my face with /join unknown command in the server window. My channel window never shows anything, when it used to, long ago. I even upgraded to this version, from the 7.38, and its still doing it.

i NOTICED A +NT SENT TO ME FROM ONE OF THE SERVERS WHEN i CONNECTED, BUT NOT THE OTHERS.

What have I done wrong, this is so annoying, cannot be channel op?

You didn't say which server you're experiencing this issue. The only reason I can think you'd be seeing this error message would be if you have a script which is sending the /join string as if it's a server command, when actually the / prefix is a way of invoking an mirc alias in the editbox. JOIN is a valid server command, but it doesn't know what /join means. However using the / prefix executes an mirc command named /join which sends the necessary command to the server which tells it to join you to a channel.

It's possible you erroneously have a script or a join-on-connect command that contains something like:
raw /join #channelname
instead of
/join #channelname