My Phone keeps locking up and freezing - all black screen

[Sim-X]

Well I don't know what to do anymore except bring it in. Lately my phone has been locking up and freezing. I mainly notice it after re-booting my phone (either power off or soft-reset) It will get to the home screen - go to sleep like usual and then if I hit the power button again it does nothing. Most the time you can still see the backlight is on but the screen is all black. Holding down the power button does nothing. I either have to take out the battery of use the reset button. Sometimes it will do it 2-3 times in a row after booting. Once it gets going it seems to be ok. Just mainly after a reset or power off. It has never been a hard reset issue just phone locks up. I was on the older hard-spl since I unlocked the phone when it first was released.

So to try and cure it, this morn I flashed back to stock, clear storage, re-locked, clear storage, unlocked it with latest hard spl, clear storage, flashed back to 01-13 mighty, clear storage - then got everything set back up. It still does it -

So not sure what the issue is but I was thinking about bringing it in, I really don't wan a refurb which I'm sure I'll end up getting but not sure if this does it with stock rom. I haven't had any problems with Mighty so not sure what is going on here or why it's doing this.

Has anyone else had any similar problems?