Strange, I just tried 32bit Win 7 Pro that doesn't have SP1 intergrated, the setup ran successfully. It looks like the SP1 integrated version has bugs.
It comes with 4GB DDR3 RAM (one slot). The original OS was Ubuntu. I tried to install Windows 7 Pro SP1 on it. The first black screen with loading bar looks ok, then the main setup blue background shows for less than a second, then goes to black screen, after a few seconds, the DVD-Rom stops spinning, the machine looks like into a sleep mode. But with 64bit Windows 7 setup, there is no problem at all. We still need to run some 16 bit programs, so we prefer 32bit windows.  Any reason why 9010 doesn't accept 32bit Windows?
Can't install 32 bit Windows 7 Pro on Optiplex 9010