If you didn't reboot after each uninstall/reinstall, please try uninstalling, then rebooting, verifying that the Opus Program Files folder is no longer there, then installing again.
Does dopus.exe (not dopusRT.exe) appear in the Task Manager process list? If it appears, does it stay there or vanish almost instantly?
Failure to start is often caused by antivirus or similar tools blocking the program from running at all, sometimes because a new version's files aren't recognised by the antivirus tool yet.
We have a built-in startup diagnostic which may help tell where the startup is getting stuck, assuming Opus is able to start at all. Here's how to access its information:
- Edit 2024: Instructions here got garbled over the years by forum changes. See this more recent thread instead: Dopus 13 not running after install - #4 by Leo