A guy got a credit card bill stating that he owed $0.00. He ignored it but next month he got another one stating they were going to cancel his credit card if he didn't send them $0.00. He called them, talked to them, they said it was a glitch and told him they'd take care of it.
The following month he tried to charge something and couldn't. He called the credit card company who again said they would take care of it. The next day he got his bill for $0.00 stating that he was very delinquent.
So he thought he had a solution. He mailed the credit card company a check for $0.00, and the credit card company's computer processed it, noting that his account was now paid in full.
A week later, the man's bank called him asking him what he was doing writing a check for $0.00. He explained and they said, "Well, your $0.00 check has caused our check processing software to fail. We now can't process ANY of our checks from that day electronically because
that $0.00 check has caused the program to abort. We are closing your account."
The man, who had been considering buying his wife a computer for her birthday, bought her a typewriter instead.