Final answer:
The cause of the norm for the InfoTech new product team to back up each of their computer's hard drives at the end of each working day was a computer virus that infected the team's network and destroyed important computer files.
Step-by-step explanation:
The cause of the norm for the InfoTech new product team to back up each of their computer's hard drives at the end of each working day was a computer virus that infected the team's network and destroyed important computer files. This incident prompted the team to establish a precautionary measure to ensure data backup and prevent such losses in the future.