CF-28, MK2 keeps shutting off ?

Alright - went from one problem to another - just fixed an issue with the F4 fuse blown causing no LCD on a 28, 800Mhz - now fixed that and getting back to the original problem that the unit keeps shutting off and comes back to login screen. I was able to put both Win2K and Ubuntu 8.04 on an OEM hardrive (had a 60G 7,200 rpm in it with same issue) and as I try to use either OS it will just go black and come right back up to the login screen a few seconds later. Never had one act like this before so I am just reaching out to see if anybody has a thought on what would cause this.
- I have determined it is not the HD and I have even removed the battery to try and isolate the problem, my fear is it is something on the board but ? Also it did do this prior to the whole blown F4 LCD fuse incident so it is is not that. No rhyme or reason to it - so no clue - thanks and as always any thoughts are appreciated -

 

Check R16 which sits near the DC jack. If the solder is cracked or it's missing, you can get some weird errors.

 

Thanks Zero - appreciate the response, I will check it out, otherwise guess it goes to the parts pile -