Has anyone had problems with plateauing due to over-exercising?

I've been consistently losing a pound a week since January. I am so close to getting into the 150's that I have really picked up the exercise in the last two weeks. The end result after two weeks is I have stayed exactly the same weight. Where I was exercising for around 45 minutes a day previously, I have been doing at least an hour and on some days up to 2 hours of cardio. This past week I also started back with strength machines at the gym. I know that I have easily burned an extra pound's worth of calories in the last two weeks with the extra exercise. My eating has stayed exactly the same and I have not fallen into eating more due to the increased exercise as is sometimes mentioned.

This is now about the third time this has happened since I started back exercising and trying to lose in January. Any time I have significantly increased my exercise for an extended period (7-10 days or more), my weight gets stuck during the entire time and then if I go back to normal exercising the weight starts to come off again but still at the slow rate of a pound a week. Any input on this? Anyone else had a similar experience with significantly increasing exercise time?

It may be an increase in muscle mass due to the extra effort. While muscle is better than fat (looks better, will burn more calories at rest) you will not see much in terms of weight loss if you are just converting fat to muscle. I would try switching back to your normal routine and see if this helps you start losing pounds again.

Often, working out (weights included) or changes in your workout can cause your body to swell up due to delayed onset muscle soreness. That is most likely the issue here. I say keep it up for a few weeks and you will be happy with the scale. =)
Also, you want to make sure you are eating enough calories for 2 hours of cardio. Also, I have heard that the last few lbs are sometimes the hardest.
Good Luck and keep it up!

Drop your cardio to 20-30 minutes high intensity some day and 40-60 minutes very low intensity other days. Within 10 days or so you will be off the plateau.

This is not technically possible. You don't just increase your muscle mass in a period of a week or two. And it's not remotely possible to convert fat to muscle - it's like trying to say that if you work hard enough you can turn your hair into lollipops... ain't gonna happen.

I think what's happening here is that your body is protecting itself from your change in routine which is just normal and it's what the body does. Suddenly you're expecting it to do more with the same amount of fuel and so it's saying to you "no Sireeee, I'm going to hold on to every calorie I got until I know what's going on!" You see, as much as we want to lose weight our bodies are hardwired to hold on to every ounce of fat we have and getting rid of it is a Herculean effort at times. Eventually if you continue this routine your body will adjust right along with it and start to lose weight if that's what you want to do.

However, losing a pound per week at your weight is no small feat. As you get closer to your goal your weight loss will naturally slow down. I would be very pleased with a pound per week weight loss. Good luck and let us know what happens.