You didn't say if the latest version of BIOS installed. And if you reboot and open BIOS setup, does that show the correct amount of RAM and the correct processor?
If BIOS is correct, then there's a problem with Windows and you may need to do a clean install of Win7, especially if an "in-place" upgrade from Vista to Win7 was done.
If BIOS isn't correct, then there may be a motherboard problem.
