I've got the same issue with my Touch N905B. About two years ago I got the image from davidfor and I re-imaged my SD card. Things seemed to have worked ok for a while. I haven't used my Kobo for ~1 year as I recently moved and finally found the device again! When I turned it on and synced it, it had a software upgrade. Since then, I've been having the issue where the device freezes after reading a book for a short period of time. Only solution I've found is to hold the power toggle for 20 seconds and then turn it back on again. Of course, I lose all data and have to find my page again - quite frustrating.
Last week I decided that I would give a new SD card a try. I found an unused 2GB Samsung SD card that came with an old phone. I imaged the SD card with the image provided by davidfor and then swapped out the old SD card. After booting it up and going through the desktop sync and software upgrades it seemed to be working much better!
Only a few days later the same issue started happening again. I'll try seeing if its related to the number of page turns or the amount of time the device is being used and report back.
As it was working perfectly when I was last using it consistently ~1 year ago - it stands to reason that the issue could be with the software updates.
Current software: 3.19.5761 (0e028f3185 12/29/15)
Is there any way to get an image with a previous software version to test my theory?
