Primary Investigator gets really nervous around me? My new Primary Investigator, who is well respected in her field, gets really nervous when talking to me for some reason. We are the same gender and both married so it's not a problem of that sort... This does not seem to happen with any other student, who she has a really good relationship with, but when talking to me, sometimes (not all the time) she really fumbles for words. This then makes me start to get nervous and our interactions sometimes become awkward. How should I improve our relationship so I can communicate effectively with my advisor?
I would advise you to simply ask about it, in a way that pre-supposes as little as possible.  For example, you might say something like:


  Can I ask you about something I am feeling concerned about?  I've feel like our interactions become very awkward and stumbling sometimes.  When I see you talking with other people, however, I do not see this happening.  I'm concerned about this, because I want to have a good advisor/advisee relationship and be able to communicate effectively with you.


Don't assume anything about her feelings---what you might be interpreting as feeling nervous might be something else entirely, even just a mannerism of your PI.  You also may be incorrect that this is unusual with you: people have strong observational biases and also you don't see your PI when she's alone with other people.

Hopefully, the two of you can then have a short awkward conversation that will help resolve (or at least allow you to work effectively despite) your other awkwardness.