I waited two hours before starting my slow-cooker. Will the food be safe to eat?
The general rule is that food can only spend two hours in the 'danger zone'. Leaving it out for over two hours before starting the process of heating it out of the danger zone means that it could now be unsafe. 

Cooking it for seven hours on high will probably kill all bacteria in the food, however, it is not the bacteria you need to worry about. The problem is if the bacteria have produced any kind of toxin. These toxins are generally proteins, which will not be destroyed at any normal cooking temperature.

I would recommend following your username and throwing it out.