Having your software stolen after they request a 30 day trial.
In 1999 someone from the Korean company called up and asked if we could certify our software to be Y2K compliant.
In the end the product was dropped because there's a lot of effort that goes into making an application a product you can sell to other companies, and we would have had to grow our organization more than the higher-ups wanted to grow it. Things like fancier interfaces, license enforcement, documentation, packaging, 24 hour support, etc.