Congratulate your anxiety/paralysis on being right, and do not try to overtly solve the problem. Instead, try moving the situation forward in one or more ways:

- Documentation: Write up the history of the problem, when it occurs, which users are affected, what previous work has been done toward solving the problem, etc.

- Reduction: Only look for limited solutions - proving a few of the "easy" cases for some difficult mathematical theorem. Patches or work-arounds that only reduce the impact of a computer program failing. Chemical synthesis of a less-tricky part of a complex organic molecule.

- Counter-example: A counter-example can be literal - the problem was to prove a mathematical theorem, and your counter-example proves that the theorem is wrong. Or, it can be a proof that the problem is impossibly difficult. The mathematical theorem you were told to prove is equivalent to the Axiom of Choice. The computer programming challenge is equivalent to P vs. NP. The physical theory/device you need to create would violate the laws of thermodynamics.