The iPod cannot be synced. The disk is not available.

For weeks now I have tried to unsuccessfully sync a Gen 6 iPod to my PC running Win 7. I had this issue several years ago when the unit was under warranty. When I called for help, I recall having to uninstall several Apple programs and restore them in a specific order. Since I am writing for assistance, I obviously forgot those instructions. I get this error message:

"The iPod "Bob's red iPod" cannot by synced. The disk is not available.

I can't find anything on the web to resolve this and would appreciate some assistance.

Thank you.