Please double check the settings in Options > Audio > Output mode settings...
If an ASIO driver comes or goes, it could cause JRiver to be pointing to an unexpected device.
If you continue to have problems, please start a new thread and we'll troubleshoot more.
As I described in 18.0.120 thread, I am unable to use ASIO in this version - playback does not start at all if ASIO is selected, and clicking on "Output mode settings" in Options freezes MC completely -> crash.
This was (and still is) working fine in 18.0.106
My audio card is RME Fireface 400 with latest driver installed.
I can't "double check" the output mode settings (as suggested) when ASIO mode is selected, as clicking it (settings) causes MC to freeze completely without opening the actual settings window. For the other modes (Direct Sound, WASAPI etc.) I am able to open that window.
Again, ASIO output mode works fine in 18.0.106 e.g. I just installed 18.0.106 over 18.0.120 -> ASIO works well. Then I installed 18.0.120 over 18.0.106 -> ASIO does not work at all and MC freezes. Therefore I am sure it must be some MC's issue as I have no problems at all with my audio card using ASIO in other applications.