Hi dawlaw,
This is an Adobe software bug. Acrobat X pro and standard both install correctly if no other Adobe products were ever installed, but both disrupts the install (fail to create the AppData\Security sub-directories) if another Adobe product that did not create the AppData\Security directories was installed first. Adobe only tested installation on machines that never had other Adobe products installed. They didn't consider that other Adobe products may have been already installed.
Solution 1 (safest)- a) Uninstall all Adobe products from control panel, b) then delete (or rename) the \AppData\Local\Adobe, \AppData\LocalLow\Adobe, and \AppData\Roaming\Adobe directories - Adobe never cleans these directories after uninstalls. c) Do a clean install of Acrobat X pro or standard before reinstalling any other Adobe product.
Solution 2 - Copy \AppData\Local\Adobe\Acrobat\10.0\Security and \AppData\LocalLow\Adobe\Acrobat\10.0\Security from another machine that works.
Regards,
Aadesh