Hmmm... it seems the only thing I can think of is for you to attempt to start all over. Sometimes the "order" you do things will mess up Windows.
Ok, we're going to try something here. It'll involve several steps...
and download USBDeview. Save the zip file to your desktop, create a new folder on the desktop, and unzip the files into the new folder. We'll use this later.
Now, do this...
Disconnect the scanner.
Uninstall the software, hopefully it's in Control Panel > Add/Remove Programs
Go into Device manager and delete the Scanner reference.
Restart your machine and check to make sure the scanner reference is gone in Device manager.
Now Open the USBDeview folder. Look for a green icon named USBDeview and double-click on it.
In the window that opens, look for a scanner reference and delete it by clicking on it once, then going up to the File and choosing "Uninstall Selected Devices". Confirm "Yes" at the prompt, then restart your machine.
Next... (and this may have already been the way you attempted installation)
Install the software
Connect the scanner, and turn it ON
If Windows launches the new hardware found window, then point it to the folder the scanner software was installed into, and see if it'll install the software (again) for you.
Let me know if you have any problems with doing any of this.
By the way, I don't want to experimentally install the scanner software onto my computer, (please forgive!), so I have to ask you... did the scanner software you downloaded actually run through an installation process, or did it simply "extract" some files to a folder located on your hard drive, requiring you to go to that folder and run the setup installation?