Clutching at straws ...
Restart the computer.
Start ADE with the reader not plugged in. Plug in the reader and see if it appears.
If not, unplug the reader, stop ADE, plug in the reader and restart ADE.
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Alternatively ...
As the reader is now authorized, you can get DRM books onto it by copying using a file manager (sideloading).
This may be a little less convenient than using ADE directly, but should at least work (fingers crossed).
Use ADE as usual to access the .acsm files and to download the DRM .epub files.
Now use Windows Explorer to copy the .epub files from the computer onto the Sony.
The books will be in a directory somewhere like C:\Users\<userid>\Documents\My Digital Editions,
probably a little different on XP (maybe My Documents\My Digital Editions, or ...???)
If you open a book for reading in ADE1.7.2 and hit ctrl-I it will give information including where the file is stored.
The Sony will probably show up as a drive called Reader, for example G:;
copy the books into the 'Digital Editions' folder on that drive.
'Safely remove' the Sony, unplug it, and you should be able to read the books.
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