I was having the same problem and installed a battery app that reported charge/temp etc. Everything was fine while used for approx 15 mins, but as the temp started to rise thats when rebooting happened. Tried new battery but made no diff, tried a number of roms to no avail.
having the same probs... random reboots...
dell streak 5
simple streak 1.2
bootloader in the beginning shows DELL in a circle and ! in a triangle. on pressing the power button it lists the v0,3,2,7-DoctorWFix menu...
when choosing update from sdcard option, it says
E:Can't mount /dev/block/mmcblk1p1
(No such file or directory)
E:Can't mount /sdcard