No, I'm a Mac and Linux user.
I figured it out... If I opened a new book it worked, but when I went back to the current book it still had the white borders.
The solution to get an old book to re-cache the cover
1. Switch to a new book (never opened), it should have the black letterboxed borders.
2. Plug up the Kindle, and go into the linkss folder.
3. Delete all the covers in the cover_cache folder except the current book (the new one) and the ones labeled default.
4. Also, delete the cover in the overflow folder.
5. Disconnect the Kindle and reboot.
6. Now switch to the book that you were reading (that still had the white), let it go to sleep. It should have re-created the book cover with black bars now.
Last edited by just_jeepin; 02-06-2013 at 10:25 AM.
Reason: Added a solution