Mid 90s, can't remember the tech (VB, C, Java?) In the very last hours before an important demo one of the programs stopped working. Not always, only every seco

Mid 90s, can't remember the tech (VB, C, Java?) In the very last hours before an important demo one of the programs stopped working. Not always, only every second time we run it. No version control, no unit tests. It's obviously some side effect but debugging it before the demo and making changes could make it worse. Maybe it won't even run anymore, anytime. We decide to wrap it into a script that starts it, kills it, runs it again. That worked and made us pass the demo.