I purchased Office Professional 2010 and started to install it.  It asked for the Key before it started, so I entered it and it installed the complete program.  Now, when I enter an individual program such as Word or Excel I get a message stating the key is not valid.  The box was sealed in plastic with the MC multi-colored seal intact on the box and the key was inside the box.  Any idea what the problem is.  I bought it on e-Bay from a seller that had very good stats and the reviews from others who bought the program had no problems and said how easy it was to install it.

Hello Ted,

Can you try opening Word > Files > Help and on the right you should have something like "modify product key" or "Activate office with key". Use the same key and if it doesnt work then you key might be already in use...

Hope it help and solve your problem.

Hi,

the Onliine Solution Wizard http://support.microsoft.com/kb/836178 
may explain the issue - if your computer has a trial/preload, you may actually have two installations of Office (two different types) and one is activated, the other is not activated.