This is likely 50% of the possibilities.
I rarely sign up for a site just to make one post, but...
Got this error, myself. Trouble is, can't press "r", can't boot from any discs (and, yes, had an OEM) and most times couldn't even get to the BIOS--and when I could the keyboard wouldn't let me navigate within the BIOS.
I build my own pc's, but I've been bad with this one, in that, I'm keeping IDE HDDs alive with a PCI card (nightmare to set up) so the primary HDD is OH about 8 years old.
After multiple reboots and trying to boot to disc and then just trying to get into the BIOS nothing would respond to me. Again, on the very few times I could get into the BIOS I couldn't move around to check boot orders, etc.
So....started to think..."that drive is kinda old, huh?" I haven't replaced it yet, but here's what I did next...I cut the power to that old master HDD, then powered that old HDD again, and rebooted.
Now I don't get the configsys error in the subject line here....I get "cannot find OS" over and over. Sorta makes me think HDD bad.
Haven't thrown in a new HDD yet, but all the above says the thing finally died. I get a successful post "code FF" with my board and even the gleeful beep, but even the BIOS was being quirky. This said to me that BIOS is saying "I see all your hardware, but your HDD is going in and out so I'm going in and out because I can't finger it regularly". Where a post should be all or none the HDD going in and out, I think, screwed with the limited brain of the BIOS; I could get in at times, but not move around; because to get a post it should be an all or none process with the hardware.
I guess my question would be, with my setup, and I DO have SATA drives, If I throw a new primary SATA HDD in there is it going to go for my remaining secondary IDE backup drive to format to? That would be bad, m'kay?
Anywho...I think this smells of hardware to me. If you know what you're doing, pull the power on your master HDD, then plug it back in and reboot. If BIOS can't even find the OS at that point, I think this is a dead drive issue.