File or Directory is Corrupted and Unreadable

I am having this same issue. It happened once and i just reset the ipod which meant i had to put back on 2000 songs, this was not a cool thing to do as i don't back up my songs....i'm relatively ignorant to this technology thing. I can use it but when problems arise i'm stuck. So now this is happening again, it's been a month since i resent and reloaded my songs. And yes, I will admit i download and not always from itunes. when i am playing songs on my computer with the ipod i'm also getting a message that says "the ipod cannot be updated the file or directory is unreadable or corrupted" so i cannot add anything new to this which is a pain as I'm a Middle eastern dancer and need to add new music to my ipod constantly. It's two different messages, one when i connect the ipod to the computer and itunes first opens and then in between songs when i'm playing it on my computer....someone help us...why is it doing this???