Digital BW, The Print

I have one file that always prints with a keyline. There is no  
keyline in the file and on the print driver, where it asks you if you  
want a keyline, I have checked "none." Yet, there it is, every time.  
And, no other file does this. Does anyone have any ideas what's going  
on? I'm on a Mac and am printing with a 2200, and it's a color file,  
OEM inks.

Thanks,
Barbara White