When we were very close to release of the first version of our product, I found a bug in which the product crashed on entering the license key :). Debugging the issue was a lot of fun for developers and regardless to say the bug got immediately approved and also made us think - Are we actually ready to ship? We released the product after fixing this ship stopper.
-- Anand Thakker
Do you have a bug whose story you love to tell? Let me know!