My big problem is actually not checking the traffic as often as I should be. I mean, I do look at the cars around me, but I don't look beyond them.
There's actually nothing wrong with my speed at all; in reality I am an incredibly cautious driver.
Fortunately, I do try to give myself as much space as I can when changing lanes...mostly because I currently drive an old station wagon that's slowly on its way out.
I've yet to have an accident, but I have come close a few times =/