Hmm..This just pop into my mind as I read your comment.

Could you use this specific scenario to view how the candidate would react? If he starts to complain that the right tools are not on the laptop, or he is unfamiliar with environment, does it is signify that he is focusing too much on the tools rather than on solving the problem?

Maybe his time management skills needs some work, ie limited time to solve the problem and too much time worrying about environment.