Have just foolishly installed T Mobile's mobile broadband software on my MacBook Pro, which runs Snow Leopard. Having now done the restart I was told to do by the T Mobile software - the MacBook Pro now won't start up! It gets stuck on the startup screen with an endlessly spinning pinwheel, and that's it.

Help! I've tried forcing a shutdown and restart a couple of times using the power on/off button, but sadly I still have the same problem.

Is it possible that you might experience trouble with your hard drive. Its possible that hard drive got stress too then it will make the pc become slower. I will suggest that you should re-plug the RAM you might find the answer there.

I think problem like this involves hardware such as RAM, processor or video card. I got same problem with you sometimes. since I am using desktop all I have to do is to pull out my RAM's and try to clean the RAM slots. then replugging HD cables just to make sure. Then voila its done.