Have you by any chance disabled ACPI?
I only recently found this problem... and it's strange since I've been using Windows 7 since early 2009 but only now I have experienced this issue. Some of the things I did might have triggered it.
For starters I didn't use to turn off the surge protector... I just left it open, but recently I wanted to do some power saving and turned off the protector after I closed the computer. When turning it on, sometimes I get the bug. All I have to do to fix it, just that it won't work every time, is to turn it off, wait a few minutes, turn it on, wait another min or so and then power up my pc and the loading goes normally.
I also managed to quiet the bug by resetting the BIOS. The strange thing was that I was constantly resetting the pc hoping that in one of the tries the clock would sync, and everything would work fine, but suddenly the BIOS said it wasn't able to load some parts of it and it gave me the option to reset. I reset it and it worked fine... for a while.
Some of the settings that I've changed were UMA frame buffer for my 780G from 256MB to 64MB. I know Ultimate requires at least 128MB, but it works fine with 64 nonetheless, setting remained.
I've had Cool'n'Quite disabled, and only recently enabled it.
Right until I did some research as to what this bug might be, I noticed I had ACPI 2.0 disabled. Which was strange since I can remember enabling it a few months ago.
And last, and somewhat worring, I've updated the BIOS to the latest one, being from 2009, which might have introduced this bug. I'm not sure and I can always go back to an older one if the bug persists, since it didn't fix my SPD issues... I have DDR2-PC800, but they only runt at 667, even if Brisbane supports PC800 and they are set at 800Mhz in the BIOS.
Asus M3A78 Pro, Athlon 5600+, Win 7 x64 U, 2 GB RAM.