I have a HP Pavilion 500 running Windows 8.1 and it won't boot up. The HP logo appears with the twirling dots but it won't go beyond that point. Sometimes, after turning it off and on again, I get "Preparing automatic repairs" but then the screen goes black and it stays like that for ages.
I have also looked in the BIOS and the HDD is detected, and I ran a DPS test and it passed.
I have created a USB installation drive, as in the one from Microsoft's site, and tried to boot from that. Then I get the HP logo with the twirling dots for a few seconds, and then a black screen that just stays black for a long time too...
If I disconnect the HDD and boot from USB it successfully goes into install/repair mode, which suggests something wrong with the hard disk , but shouldn't it boot from USB even with it connected and just ignore the hard disk?
Just to confirm my comment below. If I open in falconfour's ultimate boot CD / MiniXp, I have no problem reading & writing to the HDD. Tried to run bootrec.exe from here but I'm told it's not a valid Win32 application - did a chkdsk and everything was fine, no bad sectors...