Recently, I've been unable to launch any of my newly downloaded files. I think it was my fifty-eighth song when it started doing this. The ones I've previously downloaded still work fine. I've tried deleting some songs that I didn't really need anymore, thinking it might be a memory problem, but to no avail. Does anyone have any advice?

I use Quicktime 6 as my player, and Mac 9.2 as my OS.

Thanks in advance.