Like several others I have the SD card problems. Additionally, my KT now and then acts on its own:
(a) I had the KT sitting on the table with nothing clode to it - and it suddenly changed from 'airplane mode' to being connected to my network (by WIFi)
(b) when it has 'lost' the SD card it sometimes re-finds it WITHOUT any action being necessary - just letting it be is enough to regain the SD books
Further, it used to be that it took several minutes to "process content" after a power-on. Now it takes less than a minute, but the percentage processed is shown as 6%; bot when it starts processing and when it goes on to the home page.
Oh well, since I keep my books on a side loaded SD card, I guess I will have to revert to dead trees until Kobo releases an update.