Topic: "Audacity already running" problem

HI,

I'm running ubuntu 12.04 with a UA-25 EX.
Audacity worked for a few times. But suddenly I get the warning message "The system has detected that another copy of Audacity is running...." and I can't open it. I killed the task, and I reinstalled and rebooted a few times too. Any idea?

Please help.

I didn't find the right solution from the Internet.

References:
https://forum.audacityteam.org/viewtopi … mp;t=67814
Infographic design studio

Thanks!