If possible, mount your CD ROM drive into one of the lower brackets to resolve any possiblity of overcrowding the power supply. If the CD ROM wiggles at all when that door opens and aggrates any shorts in the system you will get the freeze. (I wish case makers would figure this out!) Idealy no wires should be taught, and no connections pressured or rubbed by other components when access doors, slides, or panels are removed.
I pretty much just leave the side of my case open for the access and air-flow, but the extra room for cable to expand and self-tangle are good too.