New to AE so please understand if this is common but, every time I drag a new image into my timeline thing on After Effects the ability to playback using the spacebar tool just stops. It just switches to the hand tool even if it's a quick tap and release.
You are either holding it too long or you have an issue on your system. The spacebar doubles as the view panning "hand" tool, which many people are completely ignorant of and that's perfectly normal. Anything beyond that simple bit of truth would require proper info about your system, keyboard and language settings, hardware acceleration settings in AE, preview settings. If it occurs all the time, chances are your system simply isn't equipped to handle AE properly or there is a serious configuration problem. Eitehr way, more info is required.