Accidentally tarpitted prof's office hours by asking a question about one of the assignment problems. Turns out the obvious approach gives a non-physical result and he can't figure out why.
This sort of thing just follows me around, I'm not trying to cause trouble, I swear.
Based on what the prof said today, it sounds like I accidentally tarpitted his whole day, not just office hours.
In summary: The answer key for the textbook he got it out of has the naive, non-physical solution. He and the TA got far enough to confidently say that the correct solution is absolutely not an undergrad E&M problem.
Does not follow the laws of physics. In this case, the electric field has a nonzero curl even though there are no changing magnetic fields, which violates Maxwell's Equations.
(If any physics nerds want details, I can give a description of the problem and why the result is non-physical, but I'll hold off on that until somebody asks.)