Word 97's Elusive Bug Vanishes in Debugging Limbo

The Word 97 release cycle was marked by a mysterious bug that defied detection. A defect surfaced in the test labs, but vanished when engineers tried to debug it.

Veteran Microsoft engineer Raymond Chen recalled the experience: 'The development team was very anxious, because a bug that appears only sporadically in the lab is going to occur regularly in the wild.' The team struggled to find a solution as the bug refused to cooperate with debugging tools.

Theorizing that the issue might be related to the CPU, the team turned to an In-Circuit Emulator (ICE), but acquiring one seemed like a distant prospect. Eventually, they discovered the problem was caused by a specific manufacturer's CPU erratum and traced it back to a compiler update.