Strange kernel reboot (oops?)

Hi, While running an embedded linux platform (sh4) with an old linux kernel (2.6.23), I'm trying to debug a very strange behavior (at least strange to me). The box is running aparently fine, and out of nothing it is rebooting. There is no "Caught signal ..." message, no kernel oops message, just a plain cpu reboot. After the reboot, the linux kernel boots but somewhere before running the user application it panics. The kernel panic message seems useless, because the system is booting. When power is unplugged and re-plugged, the system starts normally. Has anyone seeing this kind of behavior before? Thanks, Ezequiel.