While you didn't say so, I'm assuming you're getting a warning from the HIPS section of the file shield, as I was getting when trying to boot-defrag with Puran. If you go into Settings/Resident/File Shield/Sensitivity, down at the bottom you'll see a setting for HIPS (misbehavior) sensitivity showing three columns.
Try lowering the HIPS sensitivity a notch/column at a time, rebooting each time, and see if that helps. In my case, I found that with the intermediate setting (2 columns lit), Puran could boot-defrag fine and I still had a fair bit of HIPS protection active.