Why we don't "harp" on this

על נהרות בבל...על ערבים בתוכה תלינו כנורותינו

Along the rivers of Babylon...because of the Arabs in our midst we hang up our harps

Why should we do this? Simple reason is that since the destruction of the temple and goyim are in our midst, we can't be happy and play music. A possible more direct connection... תיקן חצות is THE best antidote to our temple-less existence. King David also got up at midnite every night to learn and daven. How did he know when to wake up? His harp that was suspended over his bed would begin chiming from the blowing of the North wind exactly at חצות. Thus since ערבים בתוכה we need תלינו כנורותינו to wake up for חצות to rectify the situation.

Rabbi Goldman's comments:

Nice play on words.
That word is also alluding to the other half of our problems in golus - Eisav as follows:
Aravim - in "A-T B-SH" is transformed as follows:
Ayin = Zayin = 7
Reish = Gimmel = 3
Beis = Shin = 300
Yud = Mem = 40
Mem = Yud = 10