Every time i connect to mirc, my firewall says that it has blocked an attack attempt on my computer from a certain IP adress (always the same one).

It claims that this IP was running a portscan on my computer, and it's on different port numbers each time.

So i was wondering if this is cause for any concern or if i can just let it keep doing this. (mirc still works fine)
In other words: Does it sound like an actual intrusion attempt or something harmless?

Also, i read somewhere that some mirc servers automatically run portscans on you whenever you connect: true or false?

Thanks.