iTunes Music Library file error/alert

[Steve Talkowski]

I've been listening to iTunes all evening and from out of the blue I 
get the following alert:

"The iTunes Music Library file cannot be saved because the disk is 
full."

I don't get it.    My two hard drives have plenty of space left.  I 
quit iTunes and when restarting, it prompted me to enter info as if I 
was running the app for the first time.  I declined to have iTunes 
search my hard drive and the program started and my library was intact. 
   Now, the error continuously pops up as soon as I hit "Ok" to close 
the window.

Have any of you experienced this before?  What gives?

-Steve