shuffle won't syn model a1204

My iPod shuffle, model a1204, will not syn to add new songs I downloaded from iTunes. I have tried everything. Sometimes when I unplug the device, iTunes will not recognize it again when I reconnect it.

Other times when I quit iTunes, the PC will not shut down.

I have the latest updates. I tried going to factory settings, but that failed. Sometimes iTunes says the disk is not available.

What is the problem?