unable to sync files to my SanDisk Sport "error" no other information

I am unable to sync around two dozen songs to my SanDisk Sport! Windows Media Player shows a red x at about 20 - 30 of them with just the word "Error". no other information is showing. right clicking on the x and selecting "error details" does nothing. If I try those songs again, same "error" problem. all 320 songs are music I made myself all using the same ACID Music Studio program so I do not know why it just says error on several of them. Google does not like the search for it and I don't blame it, how in the world is "error" going to make any hits?? even when adding "Windows media player sync" to the search.

and for the record, that's a new low for Microsoft to give an error message that just reads "error" without giving any more information on what the problem could be.

Try this to remove the red x in WMP for some songs

Go to Organize (top left of Windows Media player window) Click on Options, Click on library and then uncheck Retrieve additional Information from the Internet.