The correct forum is http://forums.adobe.com/community/premiere_elements
Select a reason, then click I STILL NEED HELP to activate Premiere Elements chat
[Moved to Elements forum.]
That happened to me trying to install Photoshop Elements 12 on Windows 7 64 bit. In all my years of working with these programs, that was the first time that ever happened. Is your Premiere Elements 10 on Windows or Mac. I think that i remember some Mac issues in this regard.
Activation problems can only be corrected by Adobe, and John T. Smith's second link in post 1 can help you with that.
But, before you seek Adobe Chat, shut down the computer and try the installation again.
I was about to contact Adobe Chat, when the second or third time around, the serial number took. Servers issues??? Never did find out. And, I was not typing in the wrong numbers.
As an aside, if you have Premiere Elements 10 and NVIDIA video card, please let us know if you experience any unexplained display issues. There is an epidemic of such going around. The fix, for now, is to roll back the video card drive version. More on that as indicated.
Please update us on your progress.