The case of the glacially slow computer
So, I recently ran into an interesting issue with trying to install Windows 7 64-bit on a PC. This one was quite a puzzler, and so I thought I'd share my experience, with the hopes that it will help someone else who's desperately searching for an answer.
You see, this particular machine had been running 32-bit Windows XP for quite some time now (at least a few months, if not longer), and had been running fine. We decided to try and re-purpose the PC, and install Windows 7 64-bit on it, and that's when we ran into trouble.
You see, whenever we tried to start installing Windows 7 on this particular machine, it would get stuck at the "Setup is starting…" screen. This happened with WDS, install from a USB drive, and install from a DVD. We hadn't had this issue with WDS on any other computer, and that same DVD had been used for installing Windows 7 on other machines. (Side note: WDS skips the language select screen, but the other two methods had it freezing at the "Setup is starting…" screen after selecting the language and keyboard layout.)
One time I managed to get past that "Setup is starting…" screen by just waiting it out. It eventually installed Windows 7 after several hours. However, I found that Windows itself was extremely laggy, so much so that even moving the mouse cursor around was extremely jerky.
We tried swapping out the video card, the NIC, removing the optical drive, even swapping power supplies, and still it didn't fix the problem. Suspecting an issue with RAM, I let it run Memtest 86 overnight, and still nothing came up. I finally tried removing the second stick of RAM, and next time I booted it up, it loaded up w/o a hitch. I tried re-installing Windows 7 again and it zoomed through the install this time.
Once installed, it was quick, responsive, and the complete opposite of how it had been before, even though it was down to 2 GB of ram instead of 4.
My best guess as to why there wasn't an issue with it when it was running 32-bit Windows XP, was because that couldn't actually address all 4 GB, and there's likely an issue with that RAM that causes a slowdown of the entire system, that only happens when all 4 GB are addressable. I'll probably be doing more testing on that system next week to try and confirm if it's the RAM stick or the motherboard. (Though my suspicion is that it's the RAM stick.)