TOSHIBA A75 series are workhorses they will run and run. The only problems I have experienced with this model that is fairly common is the DC Jack fails, Overheating and onboard memory failure.
Since onboard memory can cause the above symptom, that was on of the first things I tested. The memory turns out to be fine. Opening the unit I see that there had been a previous spill that had dried and and was on some important VLSI chips. The next step was to closely inspect the spots where the spill was and visually determine if it could be the cause of failure. This depends on whether it was on any PCI or video subsystems. As it turns out it was on the PCI subsystem.