I can reproduce the problem definitively by running Pandora for about 20 min on latest proposed repos etc. I captured this info from the freeze:



==== dmesg ====
[ 7320.656032] INFO: task i915/0:272 blocked for more than 120 seconds.
[ 7320.656038] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 7320.656042] i915/0        D c08145c0     0   272      2 0x00000000
[ 7320.656048]  ed2bbf04 00000046 efbb713c c08145c0 efbb73a8 c08145c0 a4e86259 00000688
[ 7320.656056]  c08145c0 c08145c0 efbb73a8 c08145c0 a4e854a0 00000688 c08145c0 edcfbe00
[ 7320.656064]  efbb7110 ef92f014 ef92f018 ffffffff ed2bbf30 c056fd66 c0748e80 ef92f01c
[ 7320.656072] Call Trace:
[ 7320.656086]  [<c056fd66>] __mutex_lock_slowpath+0xc6/0x130
[ 7320.656090]  [<c056fc80>] mutex_lock+0x20/0x40
[ 7320.656123]  [<f08f1c0a>] i915_gem_retire_work_handler+0x2a/0x70 [i915]

==== /var/log/messages ====
Dec  1 20:20:25 dell2400 kernel: [ 8040.656041] i915/0        D c08145c0     0   272      2 0x00000000
Dec  1 20:20:25 dell2400 kernel: [ 8040.656047]  ed2bbf04 00000046 ee336000 c08145c0 efbb73a8 c08145c0 31bdeba8 000006c2
Dec  1 20:20:25 dell2400 kernel: [ 8040.656056]  c08145c0 c08145c0 efbb73a8 c08145c0 31bde544 000006c2 c08145c0 ed810a00
Dec  1 20:20:25 dell2400 kernel: [ 8040.656063]  efbb7110 ef92f014 ef92f018 ffffffff ed2bbf30 c056fd66 c0748e80 ef92f01c
Dec  1 20:20:25 dell2400 kernel: [ 8040.656071] Call Trace:
Dec  1 20:20:25 dell2400 kernel: [ 8040.656084]  [<c056fd66>] __mutex_lock_slowpath+0xc6/0x130
Dec  1 20:20:25 dell2400 kernel: [ 8040.656088]  [<c056fc80>] mutex_lock+0x20/0x40
Dec  1 20:20:25 dell2400 kernel: [ 8040.656122]  [<f08f1c0a>] i915_gem_retire_work_handler+0x2a/0x70 [i915]
Dec  1 20:20:25 dell2400 kernel: [ 8040.656131]  [<c0157a7e>] run_workqueue+0x6e/0x140
Dec  1 20:20:25 dell2400 kernel: [ 8040.656145]  [<f08f1be0>] ? i915_gem_retire_work_handler+0x0/0x70 [i915]
Dec  1 20:20:25 dell2400 kernel: [ 8040.656150]  [<c0157bd8>] worker_thread+0x88/0xe0
Dec  1 20:20:25 dell2400 kernel: [ 8040.656156]  [<c015c280>] ? autoremove_wake_function+0x0/0x40
Dec  1 20:20:25 dell2400 kernel: [ 8040.656160]  [<c0157b50>] ? worker_thread+0x0/0xe0
Dec  1 20:20:25 dell2400 kernel: [ 8040.656163]  [<c015bf8c>] kthread+0x7c/0x90
Dec  1 20:20:25 dell2400 kernel: [ 8040.656167]  [<c015bf10>] ? kthread+0x0/0x90
Dec  1 20:20:25 dell2400 kernel: [ 8040.656173]  [<c0104007>] kernel_thread_helper+0x7/0x10

==== lspci ====
00:02.0 VGA compatible controller: Intel Corporation 82845G/GL[Brookdale-G]/GE Chipset Integrated Graphics Device (rev 01)
	Subsystem: Dell Device 0160
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin A routed to IRQ 16
	Region 0: Memory at e8000000 (32-bit, prefetchable) [size=128M]
	Region 1: Memory at feb80000 (32-bit, non-prefetchable) [size=512K]
	Capabilities: [d0] Power Management version 1
		Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
		Status: D0 PME-Enable- DSel=0 DScale=0 PME-
	Kernel driver in use: i915
	Kernel modules: i915