If the DRO says it should be below zero, then it should be. My guess is a corrupt .xml. You could try restoring a backup .xml file. Look in \Mach3\xmlbackups
You'll need to rename the file to .xml
If that doesn't do it, then either create a new .xml from scratch, or reinstall.
Once set up, make a backup copy of your .xml and keep it in case of problems.