Originally Posted by degeneration
Edit - It would seem both these problems just happen for .mobi files, but not epub ones. Guess I'll be converting my library then!!
i have seen the same with my Kobo Touch and mobi files. Some mobi files have gone through OK, but some don't. My solution is the same as yours. I have left mobi as a format that can calibre can transfer to the device, but if there are any issues I manually convert it to epub.