The Ramchal in Mesillas Yesharim, Perek Alef, says that the Midrash in Koheles is referring to the destruction of the world through physical pleasures.
http://beta.hebrewbooks.org/pdfpager.aspx?req=52042&st=&pgnum=29
(It would help to read a few pages before and after as well. Also see the commentary on the bottom)
Sorry about all my ranting.