This is strange, I turned my PS3 on today at around 9pm and it gave me the same error. Obviously, this scared me a lot: I bought it used about 3 years ago, it's a launch fat 60gb with the second fresh hard drive I've put in it, a 320gb Western Digital Blue (one apparently designed for the PS3 as it generates little heat or something). This was particularly strange because I did nothing untoward last time I turned it off (except for re-downloading Warhawk and the DLC again, that's the only thing I did with it yesterday), turned it on today and it wasn't loading my background (mostly black except for a tiny photo of Brian Blessed in the corner) and took ages to do anything, the PS3 logo didn't come up. Then I got the warning, got scared, turned it off and on again and it worked fine after that. I hadn't moved it so it wasn't the HDD not seated properly, and I didn't move it to make it work again. That's probably the fourth time my PS3 has done something weird when turning on, yet every time all I've needed to do is turn it off and on again.
Was that a long post? Anyway, I don't know what causes that error but that's the first time I've ever seen it and a simple reset was all that it required. Still, if my PS3 was in warranty, I'd definitely get it replaced if I could. I don't think my luck will hold out like this for much longer, hence I've started a PS3 fund and back up all the saves I can periodically.