iPod will not sync. Cannot be found/File not found

I have a older video iPod. Yesterday I did a sync and it worked fine. Then I purchased songs from the iTunes store and now it will not sync. I downloaded the latest version of iTunes but it still won't sync. When I connect iPod I get a box saying update 1.3 is available. I have tried hitting DOWNLOAD and also LATER, but neither will work. It seems like it recognizes the iPod but then stops recognizing it (the do not connect message on the iPod screen disappears). Then I get two error messages - the first says cannot sync because the iPod cannot be found, the second says file cannot be found. I do not use photos. I have restarted trhe computer several times, reset the iPod, and tried different usb ports. Nothing helps. Any suggestions?