Last night I installed OS X 10.10 Yosemite and was looking forward to a shiny new OS that’s supposedly working very well. But unfortunately I immediately experienced problems so serious, preventing me from using the new OS seriously:

• the dock was missing, no application-switcher and worst of all, the background keept on flashing
• the whole system felt generally sluggish and slow and applications randomly hung or crashed

First I thought it is all related and probably caused by a problem with the dock – it’s not.

Yosemity background flickering and missing dock :

The flashing is caused by a bug of Dashboard. If you have previously enabled Dashboard as a space or at all, disable it; Go to the Mission Controll preference pane and turn Dashboard off:

Unresponsivenes of Yosemite & missing audio controls

The second problem was a general sluggishnes of the OS X 10.10 and apps that would frequently and randomly hang or be unresponsive. Also the audio controls and Audio itself went missing. After digging around and using EtreCheck.app i found that „[failed]com.apple.audio.coreaudiod.plist“ was probably the root of the matter. Turns out the audio-plugin „InstantOn“ used by „Airfoil“ or „Audio Hijack Pro“ by Rogue Amoeba causes all of the problems. Trashing the plugin imidiately solves all Problems: The Mac runs fast, audio returns and apps don’t crash anymore:

Open Finder, open your Harddrive and go to /Library/Audio/Plug-Ins/HAL/ and trash „InstantOn.driver“: