You probably have a hardware fault, and my first guess would be that it is a memory module or the motherboard memory control which is failing. There are quite a few threads dealing with topics like this, and a more knowledgeable techie will, no doubt, point you in the right direction. For a start, you can try removing power from the base unit, making sure you are grounded, taking the memory stick(s) out and cleaning the contacts by rubbing GENTLY with a soft eraser, and cleaning out the slots and contacts on the motherboard, then re-assemble and test. If you have more than one memory stick, try leaving each one out in turn and testing repeatedly until you get a proper boot, then the one left out is the faulty one. You might like to post some hardware deatils, as in the welcome message you got when you registered, which will help everyone to diagnose your problem.