The simplest questions are the hardest
Many of our customers are engineers or mathematicians first, and programmers a distant second. They often make mistakes which strike a qualified software engineer like myself as laughable (they'd be less downright amusing if they fixed them themselves rather than writing in to ask for help). Recently, someone reported a bug in our memory checker because it was telling him he had a leak and he couldn't see one. Turns out he was re-allocating a pointer repeatedly in a loop, but not deallocating it until after the loop terminated. Yep, that's a bug, but not in our code.
Sometimes, though, I get floored by questions which are so basic that I almost can't answer them. Right now, I'm pouring through the Fortran standard trying to find anything at all which says that variable names appearing inside strings won't be substituted for the value of the variable (eg my_string="hi"; something_else="that was my_string" - wouldn't expect my_string inside the literal to become "hi") - so far, no success. I hope they actually put it in there...
Sometimes, though, I get floored by questions which are so basic that I almost can't answer them. Right now, I'm pouring through the Fortran standard trying to find anything at all which says that variable names appearing inside strings won't be substituted for the value of the variable (eg my_string="hi"; something_else="that was my_string" - wouldn't expect my_string inside the literal to become "hi") - so far, no success. I hope they actually put it in there...