Crashes and lockups can be cause by outdated drivers, and it is usually a good idea to suggest / check the simplest and more common problem sources first.
However, for the problems entering portals or picking up items, that sounds like something with the game itself. Are you shutting down all non-essential programs (especially anti-virus) before starting the game, and did you do so when installing it? Have to tried hitting the alt key when picking up items?
