Comment 6 for bug 996008

I updated my machine with the latest 12.04 updates in the past week, which included some compiz updates (to 0.9.7.8), and the problem is still occurring.

As mentioned by Christoph, around the time of the latest occurrence I got an "irq 16: nobody cared" in syslog:

May 16 19:40:51 ntuckett-ubuntu kernel: [20742.749768] irq 16: nobody cared (try booting with the "irqpoll" option)
May 16 19:40:51 ntuckett-ubuntu kernel: [20742.749779] <IRQ> [<ffffffff810db37d>] __report_bad_irq+0x3d/0xe0
May 16 19:40:51 ntuckett-ubuntu kernel: [20742.749795] [<ffffffff810d8e69>] handle_irq_event_percpu+0xa9/0x220
May 16 19:40:51 ntuckett-ubuntu kernel: [20742.749799] [<ffffffff810d9031>] handle_irq_event+0x51/0x80
May 16 19:40:51 ntuckett-ubuntu kernel: [20742.749803] [<ffffffff810dc05a>] handle_fasteoi_irq+0x6a/0x110
May 16 19:40:51 ntuckett-ubuntu kernel: [20742.749808] [<ffffffff81015282>] handle_irq+0x22/0x40
May 16 19:40:51 ntuckett-ubuntu kernel: [20742.749883] [<ffffffffa0064370>] irq_handler

Unfortunately I was away from my machine at the time, so can't yet confirm if this was a coinciding event.