Dear friends:
I'm having the exact same problem you mention here. I'm using an Acer Aspire One with Windows XP SP3. Everything used to work just fine, but right after I upgraded my Reader Library to the 3.1 version it stopped working, it just would never start or launch even I was able to see Reader Library process on the task manager.
Anyway, here's what I did:
1. Follow the instructions on the next page:
http://sonyreader.proboards.com/inde...play&thread=46 all but reinstalling.
2. Before you reinstall the software go to
http://www.adobe.com/products/digitaleditions/ and install Adobe Digital Editions, and make sure is working on your computer.
3. Upgrade to the latest version of Adobe Reader, you can get from here:
http://get.adobe.com/reader/
4. Restart your computer
5. Reinstall the Reader Library
6. Enjoy!!!
Hope this could help you, at least it worked for me.