When debug mode is enabled, a log file should be created in System Ninja’s install directory. Usually this is C:\Program Files (x86)\System Ninja. The filename will look something like this: debug-errors-16-02-2018.log
After you’ve run a scan (that gets stuck) and closed System Ninja, would you please paste the log file’s contents here for analysis.
Regarding secure overwriting of deleted files, we’ve made a conscious decision not to implement the feature because it’s mostly obsolete on newer hard drives.