Project changes levels after Saving X3 Producer TH2 Producer

For the last week, every time I load a project, the TH2 level is set to max so it's in the red. I wind the level back, save the project, but on reloading the levels are maxed out again. I noticed this when the audio sounded worse than the last time I worked on it. Initially, I thought it could be ear fatigue, but couldn't work out how I worked  with such obviously bad a mix. It was only when I looked at all the tracks and settings that I realised they were different to their states when I saved the project.
 
The only thing I have changed is to set Sonar X3 as high priority in the task manager. I can't see how that would affect it. Any clues?