The error message may vary depending on the hotkeys that are causing the conflict. When an application that uses hotkeys starts, it registers the hotkeys that it is going to use with the OS. After that, no other application can use the same hotkeys until that application is closed or unregisters the hotkeys.
If another application has registered the same hotkeys that Recorder uses, when you launch Recorder it will complain about a hotkey conflict.
The solution is to change the Recorder's hotkeys to something that does not conflict with the other application, or to change the hotkeys in the other application.
To change the hotkeys in Camtasia Recorder select Tools > Options > Hotkeys.