Das problem dürfte folgendes sein wenn in der englischen wiki das richtige steht
"Some low-quality keyboards suffer problems with
rollover (that is, when multiple keys are pressed in quick succession); some types of keyboard circuitry will register a maximum number of keys at one time. This is undesirable for
games (designed for multiple keypresses, e.g. casting a spell while holding down keys to run) and undesirable for extremely fast typing (hitting new keys before the fingers can release previous keys). A common side effect of this shortcoming is called
"phantom key blocking": on some keyboards, pressing three keys simultaneously sometimes resulted in a 4th keypress being registered. Modern keyboards prevent this from happening by blocking the 3rd key in certain key combinations, but while this prevents phantom input, it also means that when two keys are depressed simultaneously, many of the other keys on the keyboard will not respond until one of the two depressed keys is lifted. With better keyboards designs, this seldom happens in office programs, but it remains a problem in games even on expensive keyboards, due to wildly different and/or configurable key/command layouts in different games."
Sprich auf deiner alten tastatur ist solch ein schutz entweder noch garnicht eingebaut oder andere tastenkombinationen funzen auf der auch nicht richtig ;).