So when I set out to install Photoshop Elements 11, I expected it to take some time. What I didn't expect was a fatal error at the end of the lengthy install process, followed by a lengthy rollback of the entire install. The error message ("The installation process has encountered an error while installing Shared Technologies.") was uninformative and unhelpful, just suggesting the computer be restarted before trying again. And of course it then failed again, wasting a good deal of additional time.
So I was left with searching the Web for more helpful information on the issue, discovering it to be a not uncommon problem, eventually finding an Adobe help page on troubleshooting Photoshop Elements installation problems, with a Note pertaining to my specific situation. I was trying to install from a downloaded install file on a USB flash drive. When I followed the advice in the Note to first copy the install file to the root of the system drive, the long installation finally succeeded. From start to finish the install took more than an hour (and might well have taken longer) for something that shouldn't take more than a few minutes.
The install hack is beyond the skill of less experienced users and shouldn't be necessary. The Adobe help page indicates this issue has existed since at least Photoshop Elements 9, a period of at least two years as of this writing, raising the question of why it hasn't long since been corrected, or at least more helpful information provided with the installer. Customers deserve better.
Moral: The safest way to use a downloaded Adobe installer is to place it in the root directory of the system drive (usually C:\) before installing. Don't try to install from a USB flash drive.