Pitch has shifted on project.

After recording several tracks on a project, I saved the work and shut down. When I opened the project the next day, the pitch was shifted by a little over a step. It has happened to me twice now. What is happening? Any help would be appreciated. I am using Cubase 6 on a windows 7 64 bit machine with an Echo audiofire pre8 interface.

Any chance your interface/soundcard changed it’s sampling frequency without your knowing? maybe to 48KHz from 44.1 or vice versa or something?