HOW TO REPRODUCE:
- On Ubuntu this is happening at random, but more frequently running videos on YouTube with the HTML5 player (https://www.youtube.com/html5) or with the XBMC home theatre software.

RESULT:
- Graphics hang with an homogeneous colour on screen or blank screen, and with chirp coming from the graphics card.

/var/log/kern.log (provided by another user):
Oct 25 14:53:46 lt9630 kernel: [ 737.900416] INFO: rcu_sched_state detected stall on CPU 2 (t=15000 jiffies)
Oct 25 14:55:46 lt9630 kernel: [ 857.813946] [fglrx] ASIC hang happened
Oct 25 14:55:46 lt9630 kernel: [ 857.813950] Pid: 1149, comm: Xorg Tainted: P C 3.0.0-12-generic #20-Ubuntu
Oct 25 14:55:46 lt9630 kernel: [ 857.813951] Call Trace:
Oct 25 14:55:46 lt9630 kernel: [ 857.813985] [<ffffffffa00a0d7e>] KCL_DEBUG_OsDump+0xe/0x10 [fglrx]
Oct 25 14:55:46 lt9630 kernel: [ 857.814003] [<ffffffffa00ae20c>] firegl_hardwareHangRecovery+0x1c/0x50 [fglrx]
Oct 25 14:55:46 lt9630 kernel: [ 857.814036] [<ffffffffa013ad59>] ? _ZN4Asic9WaitUntil15ResetASICIfHungEv+0x9/0x10 [fglrx]
Oct 25 14:55:46 lt9630 kernel: [ 857.814068] [<ffffffffa013ad0c>] ? _ZN4Asic9WaitUntil15WaitForCompleteEv+0x6c/0xb0 [fglrx]
Oct 25 14:55:46 lt9630 kernel: [ 857.814099] [<ffffffffa0135fb4>] ? _ZN15ExecutableUnits10CPRingIdleE15idle_WaitMethod12_QS_CP_RING_+0xe4$
Oct 25 14:55:46 lt9630 kernel: [ 857.814127] [<ffffffffa0115acb>] ? _ZN10CMMSurfaceD1Ev+0xcb/0xe0 [fglrx]
Oct 25 14:55:46 lt9630 kernel: [ 857.814158] [<ffffffffa0135e7b>] ? _ZN15ExecutableUnits7PM4idleE15idle_WaitMethod+0x4b/0x90 [fglrx]
Oct 25 14:55:46 lt9630 kernel: [ 857.814187] [<ffffffffa012e8f1>] ? _ZN15QS_PRIVATE_CORE9QsPM4idleE15idle_WaitMethod+0x31/0x60 [fglrx]
Oct 25 14:55:46 lt9630 kernel: [ 857.814215] [<ffffffffa0119d8a>] ? _ZN10QS_PRIVATE11synchronizeEv+0x2a/0x30 [fglrx]
Oct 25 14:55:46 lt9630 kernel: [ 857.814243] [<ffffffffa01233f5>] ? _Z8uCWDDEQCmjjPvjS_+0x3b5/0x10c0 [fglrx]
Oct 25 14:55:46 lt9630 kernel: [ 857.814246] [<ffffffff810871ee>] ? down+0x2e/0x50
Oct 25 14:55:46 lt9630 kernel: [ 857.814266] [<ffffffffa00cc932>] ? firegl_cmmqs_CWDDE_32+0x332/0x440 [fglrx]
Oct 25 14:55:46 lt9630 kernel: [ 857.814285] [<ffffffffa00cb260>] ? firegl_cmmqs_CWDDE32+0x70/0x100 [fglrx]
Oct 25 14:55:46 lt9630 kernel: [ 857.814288] [<ffffffff81282e5a>] ? security_capable+0x2a/0x30
Oct 25 14:55:46 lt9630 kernel: [ 857.814306] [<ffffffffa00cb1f0>] ? firegl_cmmqs_createdriver+0x170/0x170 [fglrx]
Oct 25 14:55:46 lt9630 kernel: [ 857.814322] [<ffffffffa00a9e18>] ? firegl_ioctl+0x1e8/0x250 [fglrx]
Oct 25 14:55:46 lt9630 kernel: [ 857.814333] [<ffffffffa009a9be>] ? ip_firegl_unlocked_ioctl+0xe/0x20 [fglrx]
Oct 25 14:55:46 lt9630 kernel: [ 857.814335] [<ffffffff8117939a>] ? do_vfs_ioctl+0x8a/0x340
Oct 25 14:55:46 lt9630 kernel: [ 857.814338] [<ffffffff811679ed>] ? vfs_read+0x10d/0x180
Oct 25 14:55:46 lt9630 kernel: [ 857.814339] [<ffffffff811796e1>] ? sys_ioctl+0x91/0xa0
Oct 25 14:55:46 lt9630 kernel: [ 857.814342] [<ffffffff815f22c2>] ? system_call_fastpath+0x16/0x1b
Oct 25 14:55:46 lt9630 kernel: [ 857.814345] pubdev:0xffffffffa02fd600, num of device:1 , name:fglrx, major 8, minor 88.
Oct 25 14:55:46 lt9630 kernel: [ 857.814346] device 0 : 0xffff88019b850000 .

Oct 25 14:55:46 lt9630 kernel: [ 857.814345] pubdev:0xffffffffa02fd600, num of device:1 , name:fglrx, major 8, minor 88.
Oct 25 14:55:46 lt9630 kernel: [ 857.814346] device 0 : 0xffff88019b850000 .
Oct 25 14:55:46 lt9630 kernel: [ 857.814348] Asic ID:0x6779, revision:0x3c, MMIOReg:0xffffc90012b80000.
Oct 25 14:55:46 lt9630 kernel: [ 857.814349] FB phys addr: 0xc0000000, MC :0xf00000000, Total FB size :0x40000000.
Oct 25 14:55:46 lt9630 kernel: [ 857.814351] gart table MC:0xf0f8fd000, Physical:0xcf8fd000, size:0x402000.
Oct 25 14:55:46 lt9630 kernel: [ 857.814353] mc_node :FB, total 1 zones
Oct 25 14:55:46 lt9630 kernel: [ 857.814354] MC start:0xf00000000, Physical:0xc0000000, size:0xfd00000.
Oct 25 14:55:46 lt9630 kernel: [ 857.814356] Mapped heap -- Offset:0x0, size:0xf8fd000, reference count:33, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814357] Mapped heap -- Offset:0x0, size:0x1000000, reference count:1, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814359] Mapped heap -- Offset:0xf8fd000, size:0x403000, reference count:1, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814360] mc_node :INV_FB, total 1 zones
Oct 25 14:55:46 lt9630 kernel: [ 857.814362] MC start:0xf0fd00000, Physical:0xcfd00000, size:0x30300000.
Oct 25 14:55:46 lt9630 kernel: [ 857.814363] Mapped heap -- Offset:0x302f4000, size:0xc000, reference count:1, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814365] mc_node :GART_USWC, total 2 zones
Oct 25 14:55:46 lt9630 kernel: [ 857.814366] MC start:0x40100000, Physical:0x0, size:0x50000000.
Oct 25 14:55:46 lt9630 kernel: [ 857.814367] Mapped heap -- Offset:0x0, size:0x2000000, reference count:6, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814369] mc_node :GART_CACHEABLE, total 3 zones
Oct 25 14:55:46 lt9630 kernel: [ 857.814370] MC start:0x10400000, Physical:0x0, size:0x2fd00000.
Oct 25 14:55:46 lt9630 kernel: [ 857.814371] Mapped heap -- Offset:0xa800000, size:0x700000, reference count:1, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814373] Mapped heap -- Offset:0x9a00000, size:0xe00000, reference count:2, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814374] Mapped heap -- Offset:0x8c00000, size:0xe00000, reference count:1, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814376] Mapped heap -- Offset:0x7e00000, size:0xe00000, reference count:2, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814378] Mapped heap -- Offset:0x7000000, size:0xe00000, reference count:3, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814379] Mapped heap -- Offset:0x6200000, size:0xe00000, reference count:2, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814381] Mapped heap -- Offset:0x5400000, size:0xe00000, reference count:2, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814382] Mapped heap -- Offset:0x4600000, size:0xe00000, reference count:2, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814384] Mapped heap -- Offset:0x3800000, size:0xe00000, reference count:5, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814385] Mapped heap -- Offset:0x2f00000, size:0x900000, reference count:6, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814387] Mapped heap -- Offset:0x2100000, size:0xe00000, reference count:3, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814389] Mapped heap -- Offset:0x1700000, size:0xa00000, reference count:4, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814390] Mapped heap -- Offset:0x1000000, size:0x700000, reference count:12, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814392] Mapped heap -- Offset:0x200000, size:0xe00000, reference count:5, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814393] Mapped heap -- Offset:0x0, size:0x200000, reference count:14, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814395] Mapped heap -- Offset:0xef000, size:0x11000, reference count:1, mapping count:0,
Oct 25 14:55:46 lt9630 kernel: [ 857.814398] GRBM : 0xa0003828, SRBM : 0x200006c0 .
Oct 25 14:55:46 lt9630 kernel: [ 857.814400] CP_RB_BASE : 0x401000, CP_RB_RPTR : 0x10aa0 , CP_RB_WPTR :0x10aa0.
Oct 25 14:55:46 lt9630 kernel: [ 857.814402] CP_IB1_BUFSZ:0x2d8, CP_IB1_BASE_HI:0x0, CP_IB1_BASE_LO:0x4040d000.
Oct 25 14:55:46 lt9630 kernel: [ 857.814404] last submit IB buffer -- MC :0x4040d000,phys:0x196e97000.
Oct 25 14:55:46 lt9630 kernel: [ 857.814406] Dump the trace queue.
Oct 25 14:55:46 lt9630 kernel: [ 857.814407] End of dump