There is yet another firmware version available for the JBL, .i14n on the ectaco server. I haven't had time to try it out so I don't know what changes it might have. The only big change that people are looking for is support for DRMed epub files, so maybe this has it.
FWIW, I had my first freeze up on my Jetbook Lite with the .14m version last night. It may have been unrelated to any change in the firmware, it's hard to tell. I'll flash to the .14n later tonight and check it out. Here's the link to the new firmware. At this point I don't know how 'official' it is, perhaps someone else does, meaning use at your own risk:
ftp://custftp:FQSswyvGQ20So@ftp.ecta...Lite_0.14n.exe