Optimizing with Tech Tool Pro results in error "Digital
Performer is installed and an authorization file can't be moved..."

This is a result of Tech Tool Pro's inability to effectively optimize when invisible authorization files are present which cannot be moved or rebuilt. Norton Speed Disk, among other disk optimizers do not destroy such files.

Other than using another disk optimimzer, there is a lengthy workaround: use Sherlock's Advanced Option to find invisible files that contain "auth". Delete the auth file, optimize, and reinstall Digital Performer (or whatever authorized application was affected by the error).