I totally have this. Though for me, knowing that it's common actually more or less has made it go away. I learned back in high school trying to fix computers that *nobody* knows what they're doing, and pretty much everybody is just "faking it". (Of course, there are some people who think they know what they're doing; these tend to be the people that actually know the least.) So I'm doing my best to fake being a grad student, and I haven't been kicked out yet...