My C760 has a similat behaviour (shutdown -h now or halt end up in a system reboot).
And also if I take out the battery is self reboot when I put it back in.
It I noticed this when I got the device (second hand) running an old cacko rom ... so I think it's not directly pdaXrom related.
Can I do something to stop this behaviour ?
Recently I did a test run on my c860 which, when running cacko, did not suffer from the self reboot problem.
Appart from all the other problems I found it also began to suffer from the self reboot once I had installed r121.
I thinks there may be bothe some model issue and pdaXrom issue: maybe the c760 was gesigned to work that way* but surely the c860 was not ... so pdaXrom also has something to do with the problem.
* I'm not sure because my c760 suffers from quite a few hardware problems, so it could be something specific to my c760 or something common to all c760 .... any of the guys not using u-boot on their c760 can you leave your device powered off (not suspend) without taking out the batteries ?