I was just working on an Acer laptop (not mine, eek) when I discovered it only has 512MB ram. As I was loading Visual Studio 2008, I knew this wasn't an option, so I swopped it's memory out (two DDR2's), for 1GB. When I tried to boot the machine, immediately on power on, both build in and USB hard drive lights came on and the machine hung. There was no opportunity to enter BIOS settings or anything. I replaced the original ram with no change.
I am quite confident that merely swopping the ram couldn't have cause this, but what could have gone wrong?