Product Key problems

I bought a desktop PC last year, and need to make a presentation involving PowerPoint. There is an icon marked Microsoft PowerPoint 2010 on my desktop, but when I attempt to enter PowerPoint, I keep being told to use the Activation Wizard -- when clicking "Next" on 'I want to activate the software over the Internet', it first attempts to download, then always stops and says "An unspecified error has occurred. Your request cannot be processed at this time." Then, when I try clicking "Next" on 'I do not want to activate my copy. Instead, I want to convert to the full version now", I'm told to enter my Product Key; on finding that (in incredibly small lettering) on the side of my desktop and entering it, I keep being told that "Sorry, this isn't a Microsoft Office 2010 Product Key. You may be entering a product key from another version of Office." Can anyone help, please?