i made some search about this issue with Enhanced Linux Kernel reboots

if after upgrade to PR 1.2 using app manager the issue still there and not resolved, you need to remove the Enhanced Linux Kernel files from internal memory, so to do that .. go back again to PR 1.1.1 then using xterminal as root

to get root access use rootsh app from extra-devel, then from xterminal and write this commands ..

sudo gainroot
rm /etc/default/kernel-power
rm /etc/default/kernel-boot
ln -sf /usr/share/kernel-power-settings/ideal /etc/default/kernel-power
ln -sf /usr/share/kernel-power-settings/boot /etc/default/kernel-boot

this the source .. http://talk.maemo.org/showpost.php?p...6&postcount=15

Now its should clean, just try to re-flash with PR 1.2 again, and its will work.

Good luck