Today my Gaim is not mute again. I tested a solution by somebody (but i totally forgot where did i got those instruction, sorry man) and it worked now like charm. Here's the solution when your Gaim has turned to Mute after you upgrade to Gaim 2.0.0-beta version. Open your preference window via Tools > Preferences, pick Sounds tab and choose Command for the method and then type aplay %s in the Sound Command textbox. Confused? See this screenshot below.