I have a Toshiba Satellite laptop, and it was working fine but now it's not booting at all. From some days, it running slow and hang sometimes. I was using Windows 8 Pro on this. But now it even does not boot! When I turn it on, a boot logo appears and after that an underscore sign (_) blinks and become stable and nothing happens after that. I tried re-installing Windows 8 again also I tried Windows 7 and Ubuntu but no success till now. Sometimes it boots but most of the time it fails.
One more important thing is that when I change SATA mode from AHCI to Compatibility from BIOS, it boots but it's very slow. Please tell me what's going on? Is this a hard disk problem?