Welcome to the forum.
There are any number of things that might be preventing the upgrade installation from completing.
Often and the number one reason seems to be third party security suites. It might be a little late in the game to recommend uninstalling any such software in advance of the upgrade, so....
The other reasons seem to be related to peripheral hardware devices attached to the computer.
My recommendation is to disconnect all unneeded peripheral devices, especially any wireless dongles supporting keyboards, mice or USB network adapters. I would also include even such things as USB printers or Scanners.
Leaving only the monitor, a wired USB keyboard and a wired USB mouse. Substituting wired input devices for wireless if necessary.
Sometimes even disconnecting your Ethernet cable temporarily in addition to the suggestions above will allow the upgrade to complete.
For future reference and casual perusal, when you have the time this article here....
http://answers.microsoft.com/en-us/...p-errors/324d5a5f-d658-456c-bb82-b1201f735683
Contains a lot of useful information regarding the troubleshooting of problems that one might encounter during and or after the process.
It's comprehensive but as the author admits, not entirely exhaustive.