How can I make my Sony Walkman sync again?

I've been using my Sony Walkman NWZ-A816 for about a year now, with no issues. However, recently, my Vista laptop has utterly refused to acknowledge its existence. It cannot find nor install drivers (nor can I looking online), which means it is listed as an Unknown Device. It doesn't register in My Computer or in Media Player, thus I cannot add music to it. However, plugging it in still causes it to charge. Anyone know how to solve this problem? (I've been led to believe it's common with walkmans and Vista)