Cubase 6: Changing devices changes speed and key of track.

Hello, I have noticed that when I change from device from built in driver to my POD hd bean in my older tracks the key will drop down and the speed/tempo of the track will slow down. Unfortunately on one track I accidentally saved the mistake. So my questions would be 1) what is the proper way to switch devices so that this does not occur and 2) Is there a way to correct my old track. If this question has been answered before I apologize and if you can link me the answer it would be greatly appreciated thank you.

Check your projects samplerate, against soundcard settings, you are probably switching from 44.1 to 48khz

thank you so much you are a pro