I think I had the same problem:
- the phone froze in standby (sometimes after 30min, sometimes after more than 5 hours).
- if standby is disabled it NEVER froze (but i had to charge battery one a day).
flashing was no solution (tried blue elves, onyx and tess).
i shipped it to htc-repair-center three times, but they could not repair my device (altough they tried and shipped it back to me DEFECTIVE).
Now I have a replacement Elfin which works perfectly.
HTC One M7 pre-ordered
ROM: Stock - Android Revolution HD ASAP.
HTC One X
ROM: Android Revolution HD (latest)
Asus Transformer Infinity TF700T
ROM: CleanROM Inheritance (latest)
Asus Nexus 7 3G Nakasig
ROM: Stock (rooted)
HTC HD2 (aka Leo)
ROM: JellyTime HD2 V3.0 JellyBean-4.1.2