Comment 10 for bug 995684

Same problem here. Did not, however tested what's happening when powering on with headphones attached.
Ubuntu 12.04 64bit. No Problem in 10.04 10.10.

lspci -v:
00:1b.0 Audio device: Intel Corporation 82801I (ICH9 Family) HD Audio Controller (rev 03)
 Subsystem: Acer Incorporated [ALI] Device 015e
 Flags: bus master, fast devsel, latency 0, IRQ 46
 Memory at f0400000 (64-bit, non-prefetchable) [size=16K]
 Capabilities: [50] Power Management version 2
 Capabilities: [60] MSI: Enable+ Count=1/1 Maskable- 64bit+
 Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00
 Capabilities: [100] Virtual Channel
 Capabilities: [130] Root Complex Link
 Kernel driver in use: snd_hda_intel
 Kernel modules: snd-hda-intel
Please fix, this is a no-go.