Hi Mike, sorry you are having problems. The symptoms you describe are often a sign that your graphics drivers on your computer need updating. This is just a software update for them. If unfamiliar with that process let us know.
Also it maybe the case that your PC is too old (e.g. laptop pre 2009), and that the graphics chip will not be able to handle version 4 of the software, we still offer version 3 of the software in our download sections which may be more suited to that PC.