LooseSuits

Not having a team that is multi-talented. If one part of the wheel falls off you have to have someone else around that can at least act like a spare for a bit.

Probably basing your company image around a certain set of values both publically and privately, then migrate to the complete opposite of said values. I've watched this happen to a few companies in the past, and I'm seeing it happening again (SixApart & 37Signals come to mind)

Talking and not walking. Planning but not acting. Standing still while others run around you. Not being flexible to embrace new opportunities; staying stuck in your ways and micromanaging things to death. Being too "corporate" and not willing to try out new ideas. Taking large amounts of funding, not spending it in the right places. Hiring the wrong people or hiring too many people. Hiring B and C people instead of A people.

Short-sightedness. Failure to see big picture, like cutting down on seemingly trivial costs when in the long run not making the necessary expenses really catch up to you in the end. Also failure to see where the industry you are in is moving and where it's going and always being one step behind. You need to transition your company appropriately and not go cookie cutter, but rather personalize your own company's approach rather than abandon your current customers and what you did to get you there in the first place.

Customer Expectation Management Is all about this.

There's a somewhat large movement in the business community on really putting yourself in the place of the customer, and designing (or re-designing) your business around that perspective. I know it's revolutionized several companies already, because my company is developing the systems and giving training on it.

A business will always implode if the owner is a control freak and not letting others more talented and better at specific tasks do those tasks.

The best business leaders do their best to hire those whom are smarter than they are. Its a weird concept to think the owner of a company is the least intelligent one there.

Your employees get bored and fail to maintain contact with third party service providers that are responsible for important business functions for online businesses like marketing and design. This is worse when its your C level staff.

Lack of communication. Just met with a business owner who didn't realize how lacking their communication was. The key people talked every day but not about the important things. The lapse in communication is causing everything to break down, creating a loss of efficiency and morale with the key people, which funnels down to the employees.