I have a HPdv6 and since last week I have this problem.
I tried the diagnostics, and it's all ok, everything passed, so I believe it's not a hardware problem.
Then I read that may be some mbr issue, so with an USB with Windows 7, I tried chkdisk, with no problem, then fixmbr and fixboot. The fixes didn't work, I mean, couldn't find the mbr or the boot system, or something like that, maybe now I think I haven't the permitions to do that, so...
Well, so I had the brillant idea to use Ubuntu to boot with a live usb and see if I can see my HD, and WORKED! The strange thing that happened was that when I was triyng to get on c: appears a mesage that said windows had this disk in hibernate mode, so ubuntu can't access, and asked me to delete the hibernate file to have thi access. I did the command and now I have the c: access on Linux, but stills shows up the esc message when I turn on the laptop.
I don't have any other idea...