[taming]

I have never had a Db corruption from using Calibre with the Touch either.

I have though had one with a "bad" book (in my case a public domain work) that created a severe double tap/screen responsiveness problem until it was removed. Once it was removed, there was a minor (but still annoying) residual problem with some books so I reset my device. I should have, btw, known that the book was going to be a problem because the file size was ridiculously large. Something was going on there.

All my sideloaded books are on the SD card.

EDIT:

People use their readers in all sorts of ways. I usually add one book at a time, as I generally buy one book at a time. When a problem exists, it is therefore pretty easy to know if it is likely to be a particular book that started it. People who load large numbers of books onto their devices simultaneously have a harder time figuring that part out.