This is my experience of my PS3 not booting up hope this helps if anyone else has this issue )
I turned on my PS3 tonight and it failed to boot up, it just got to the start just before the icons appear and then didn't do anything then it wouldn't shut down. I tried hard booting it a couple of times and it still wouldn't boot up then it wouldn't shut down either. So I tried to put the last game in I was playing (BUZZ) and the whole thing just crashed. Hard booted and now it's back to the icon screen and attempting to load the user but it doesn't seem to be working! Ahhhhh been trying to fix this for over an hour now! Removed the HDMI cabels and replaced with an RCA cable and tried again message came up on screen "hard drive is corrupted and must be restored" selected OK and then the message appeared again so selected OK again. I think just disconnecting the cable allowed the system to recognise the corruption. Changed the cable back to HDMI (don't think I needed to change the cable just disconect it) and reset everything and it seems to be working now! Yes I can have a go on Guitar Hero!!!!
Sounds like its definately a problem with the HD, is it a new one you upgraed or the original one?