The most probable cause is that the previous version cannot be uninstalled. To solve it:
- Restart the machine for a clean start, then manually stop all NetCrunch services.
- If any process is running (WebAppSrv.exe for instance) you can safely kill it, then uninstall the program.
- Your data will stay intact. You can now install the new version.
The problem with hanging installations has been fixed in version 9.1.4.
