I have a Toshiba Satellite 5205-S503 Notebook computer. My computer was sluggish/ unresponsive and I shut it off by holding down the power switch and it turned off. The next day I tried turning it on and I get a sound from the DVD/CD Drive (1 sec) where it attempts to access it and that's all it will do; no display and it appears that it will not bootup. On the front of the computer, if you press the "MODE" switch to "CD" and press play and plug into the audio port, it will play music. This indicates that the CD/DVD player and the sound card are OK and maybe the mother board as well. I plugged an external monitor into the DB25 port and no display. I removed the battery and inserted one SODIMM at a time in slot one and reinstalled the battery in an attempt to eliminate bad RAM as a reason for no bootup; no change, will not boot. I removed the battery and then removed the hard drive and installed it in an external USB enclosure to test it. It was not recognized and did not spin-up properly; unreadable. So far it looks like I have a bad hard disk. I don't have a way to test the processor; however, I tested the fan and it is OK therefore I suspect that the processor is probably OK. If you read my entry (GoNASA)on your site in response to someone with a no-boot issue, you will see that this Toshiba model is unique and not in a good way (please read the entry.) My question for you is: would you say that a bad hard drive could explain the failure I have experienced? In addition,is it true that this model 5205-S503, part# PS520U-2SZRHV, will only boot if it detects a correctly functioning 40GB ATA Toshiba HD model# MK4018GAS?