Sony books are all in LRF format. That format tends to crash the reader unless you transfer the file using Sony library software. See here:
So in short if you plan on using LRF format protected or not you MUST use Sony library software for transfering files. Calibre and Sony library software do not cope together well. I had three times to reformat reader while I used both programs. So for file transfer use one and only one program - no mix.
In your case you should use Sony library software for purchasing books and managing files. You should use calibre to get the newsfeeds and import downloaded feeds into sony library and than transfer them.