The version I always used to play was (and is) 1.05. Is there a new version? Could this be the problem?
Yes, you'll have to update to 1.11 in Impulse and the problem should go away 
It used to give the "wrong version detected" error to clue you in a bit, but in the 1.1 patch the ICO server port changed from 6000 to 7000 so your 1.05 is still trying to connect on 6000 and it can't, so instead of wrong version you're getting a disconnect.