What Should You Do With Your Career When Your Company Is Failing?

I read this post on the Business 2.0 blog, about a Microsoft employee leaving the company.

I have worked at five different companies. Only once did I leave a company because the ship was sinking. I could not see any way that I or the company could be successful. To me, the culture was not able of overcoming its problems.

Have you ever worked at a company that was sinking? What did you decide to do? Did you ride out the lows, and help turn around the company? Did the company eventually fail, or downsize your position? Did you leave, and if you did, why? What do you think is the right employment strategy when a company is going through challenging times?