Why is my PS one (with LCD) in a continual reset loop?

My PS one and LCD screen combo unit is susceptible to reset loops. Sometimes it will start up and play very well, and then it will suddenly reset in mid-game and reset continually.

When a reset loop occurs, the system logo screens will load while booting up, once the disc is being accessed reset will recur. Patient waiting of many resets might allow for the disc to load and start the game sequence, but upon pressing a button to go to the start/select screens (requiring the disc to be read-accessed again) will usually result in an immediate reset.

I actually have an extra PS one unit and have tested the same LCD screen on both units with identical results so I suspect the problem has something to do with power flow from cable head to LCD to PSone unit that is somehow affecting proper functionality,