And so I would believe that it may not be an issue of corrupted driver
( unless the driver in the Windows Repository itself is corrupted in someway.)
You seem to have done almost everything, including searching for the driver in winsxs.
Now I remember that once A Guy recommended to the OP to power cycle the PC and it worked.. So do it now.
1. I think yours is a desktop. Shut down your PC and pull out the plug from the Mains socket. Leave the PC off for about half-an-hour so that it dissipates all charges that might have built-up. For a good measure press the Power Switch on your desktop for about ten seconds. Then connect the mains power and boot your PC. (If it is a laptop, you will not only remove the mains power completely, but also remove the battery pack.) This worked magically for many users.
2. If that does not fix your problem, try the Microsoft USB Fix Tool. USB Fix It: Official Microsoft Tool To Repair Removable Device Issues
3. Finally carryout all the procedures I had outlined in my post I had referred in my previous post. You had done only the procedure 2. Now do 1. Removing all non-present devices and 3. Rebuilding the infcache.1 file.
If all this doesn't help as I said in that post, "If after this complete USB rebuild, the problem is not resolved a repair install, I would think, is the only option left. http://www.sevenforums.com/tutorials/3413-repair-install.html "
I think that this has also been stated in the first about.com article you had referenced in your first post.
If you do fix it by any other means, please let us know.
Note: Whenever a system malfunctions for reasons not known, it is customary to check the system for any malware. Have you done it?