I'm having a few "problems" LOL

I'm using an EPIA machine, with a Morex 60W InCar DC PSU and a 7" TFT touchscreen from LinITX. The machine itself is very basic - a 2.5" HD, a slimline DVD drive, and the touchscreen connection via USB.

With the ignition in ACC, the PC and LCD both power up fine - 100% reliably. With the car started, the PC always powers up, but the LCD only powers up after 1 in 10 engine starts if I am lucky

I also have a problem with alternator whine. A ground loop isolator on the RCA fixed that - but only whilst the PC is on. Not too much of a problem, but wasn't sure if it was related.

The PC and the LCD are both powered atm from the old head unit power connection - split off and running into each. In an attempt to eliminate the grounding problem I ran another ground cable to the boot where the amps are and grounded everything in the same place. No change This grounding point is shared with the rear lights - is it worth tapping another?

Aaaanyway, is it possible that the 12v to the LCD is not within it's tolerances? Is there another way I can run this LCD - for example would one of the 12v lines from a drive power connector be sufficient? Am I going to have to tap another source, or find a way of regulating the power?

All input gratefully recieved