An extremely annoying bug/feature of ACE is that it spins up all of my hard drives every time I join a server. I have six hard drives, and waiting for them all to spin up before I can start playing is extremely tiresome.
I'm aware ACE makes use of system hard drives as part of creating the hardware ID, but I really think this "feature" needs to be retired. Firstly because well-engineered programs should not access a system's dormant hard drives unless explicitly required to; and secondly because it makes it stupidly easy to change your ACE hardware ID (by adding or removing a hard drive).