"Remember that one bug that had you tearing your hair out and banging your head against the wall for the longest time? And how it felt when you finally solved it? Here's a chance to share your greatest frustration and triumph with the community.
One that I vividly recall occurred back in the early 90's at a startup that was developing custom PBX hardware and software. There was the current development prototype rack and another rack for us in Quality Assurance (QA). Our shipping deadline for a major client was fast approaching, and the pressure level was high as development released the latest hardware and software for us to test. We soon discovered that our system would not boot up successfully. We were getting all kinds of errors; different errors each time. Development's machine booted just fine, *every* time. We swapped out our hard disks, the power supply, the main processing board, the communications boards, and finally the entire backplane in which all of these were housed. The days passed and the system still failed to boot up successfully and gave us different errors on each reboot.
What could it be? We were all stymied and frustrated as the deadline loomed before us. It was then that I noticed the power strips on each rack into which all the frames and power supplies were plugged. The power strip on the dev server was 12-gauge (i.e. could handle 20 amps) but the one on the QA rack was only 14-gauge (15 amps). The power draw caused by spinning up the drives was just enough to leave the system board under-powered for bootup.
We swapped in a new $10 power strip and it worked perfectly. And we made the deadline, too! So, fellow Soylents, what have you got? Share your favorite tale of woe and success and finally bask in the glory you deserve."
Not being a "real" programmer, my personal favorite involves HTML/CSS. About 8-9 years ago I had coded a web page template in a basic three-column format. The three columns had unique IDs (IIRC: col1, col2, and col3). The page rendered correctly in all browsers... except Internet Explorer. (Heard that before, huh?) But I could not figure out what was wrong. The HTML and CSS validated. I wasn't tripping any IE bug that I knew of. After endless fiddling, for some reason I changed col2 from an ID to a class in the CSS and the HTML, and the damn thing rendered fine.
I swear, there were no errors or naming conflicts anywhere in the code. (I write very neat HTML and CSS, and was once complimented by a "real" programmer that my code looked like something from a textbook.) I Googled around and never found anyone who had ever reported a similar problem. To this day, I have no idea what the bug was or why that solution worked.