i've fixed my stability issues. this is what i did:

1. remove speed patch and battery patch.
2. revert back to stock nokia kernel (remove kernel power v48)
3. upgrade to latest CSSU
4. reapply kernel power v48
5. reapply speed and battery patch.

the device no longer suffers from random reboots. it's been stable for the past 6 hours. as a downside, i can no longer enable smartreflex (it used to be stable for my device). that's a small matter really.