Here are some points of clarification: The power supply's fan starts, in fact it isn't a problem at all. When start-up crashes the fan keeps going like the Energiser bunny.
I tested the RAM sticks individually and took out the only one with a problem. The other two are both Kingmax PC2700 512 MB Ram. Is there anything else I should know to match them?
The start-up process actually begins and runs through the usual memory test etc. prior to starting Windows. Sometimes nothing happens but the fan kicking in. It seems that if the DVD ROM light comes on immediately, it doesn;t start, but if the light on the DVD Rom flashes, disappears and then the DVD Rom fires up, the start-up process begins. Hopwever, this is no guarantee that start-up will run successfully. Sometimes I get through log-in to Windows and start an application and then BLANK! The screen goes to a default message that says something about "system not plugged in" or something and the system has crashed. I get no blue screens only blank......
Sorry, but this is as much detail as I can offer right now.