Hi there.
The latest firmware versions should work on a Touch so something else may be causing the problem. Usually the most likely cause is either a corrupt database or 'sickel' kicking in and rebooting the device due to the processing of a complicated ebook taking too long.
To test the latter hypothesis you could try stopping sickel from triggering automatic reboots by installing frostschutz's hack, see:
https://www.mobileread.com/forums/sh...5&postcount=28