There are several files that Wall Worm generates that it uses over time. Sometimes those files can be corrupted and cause Wall Worm to stop working correctly. Sometimes the symptoms include seeing an error "Unknown System Exception" or other errors.

The easiest way to fix these errors is to delete the utility files.

1. Click Wall Worm > Wall Worm Utilities > Check For Problems
2. Click the Purge Utility Files Button
3. Check all available options and click Delete Selected Files
4. Restart 3ds Max