I got this message when plugging in my ipod to my computer.
The solution seems to be this (at least it worked for me):
1. I clicked ok, then waited for the sync to complete. It appears that despite the message it still syncs but slowly and sometimes not all the files are synced with this error. I then unplugged my ipod and closed itunes.
2. Go to Control Panel > Administrative Tools > Services. Select 'Apple Mobile Device' and on the left side click 'Stop the service'. After it has stopped then select 'Start the service'. Then try opening iTunes again (I just plugged in my ipod back in and that launched itunes)
Solution was found towards the bottom of this page. The message board has a lot of different solutions that seem to work for some but not for others