I can confirm this bug on my Dell Vostro 1710 running Jaunty (2.6.28-11-{generic,server}).
It occurs only once on every boot, when GDM starts (and thus does its prefetch), provoking a ~30s blank screen with heavy disk activity before the login screen.


[   80.040094] ata1.00: exception Emask 0x0 SAct 0x7fffffff SErr 0x0 action 0x6 frozen
[   80.040106] ata1.00: cmd 60/88:00:25:76:72/00:00:08:00:00/40 tag 0 ncq 69632 in
[   80.040107]          res 40/00:fe:00:00:00/00:00:00:00:00/40 Emask 0x4 (timeout)
[   80.040112] ata1.00: status: { DRDY }
[   80.040118] ata1.00: cmd 60/08:08:7d:63:d4/00:00:07:00:00/40 tag 1 ncq 4096 in
[   80.040120]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040124] ata1.00: status: { DRDY }
[   80.040130] ata1.00: cmd 60/08:10:8d:cb:81/00:00:07:00:00/40 tag 2 ncq 4096 in
[   80.040132]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040136] ata1.00: status: { DRDY }
[   80.040142] ata1.00: cmd 61/08:18:b5:64:f8/00:00:07:00:00/40 tag 3 ncq 4096 out
[   80.040144]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040147] ata1.00: status: { DRDY }
[   80.040153] ata1.00: cmd 61/08:20:45:e1:f8/00:00:07:00:00/40 tag 4 ncq 4096 out
[   80.040155]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040159] ata1.00: status: { DRDY }
[   80.040165] ata1.00: cmd 61/08:28:ad:d4:f9/00:00:07:00:00/40 tag 5 ncq 4096 out
[   80.040167]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040171] ata1.00: status: { DRDY }
[   80.040177] ata1.00: cmd 61/08:30:c5:58:fc/00:00:07:00:00/40 tag 6 ncq 4096 out
[   80.040178]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040188] ata1.00: status: { DRDY }
[   80.040191] ata1.00: cmd 61/18:38:4d:e1:f8/00:00:07:00:00/40 tag 7 ncq 12288 out
[   80.040192]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040193] ata1.00: status: { DRDY }
[   80.040196] ata1.00: cmd 61/10:40:25:fa:f6/00:00:07:00:00/40 tag 8 ncq 8192 out
[   80.040197]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040199] ata1.00: status: { DRDY }
[   80.040201] ata1.00: cmd 61/10:48:45:fa:f6/00:00:07:00:00/40 tag 9 ncq 8192 out
[   80.040202]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040204] ata1.00: status: { DRDY }
[   80.040207] ata1.00: cmd 61/08:50:5d:fa:f6/00:00:07:00:00/40 tag 10 ncq 4096 out
[   80.040208]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040210] ata1.00: status: { DRDY }
[   80.040212] ata1.00: cmd 61/08:58:6d:fa:f6/00:00:07:00:00/40 tag 11 ncq 4096 out
[   80.040213]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040215] ata1.00: status: { DRDY }
[   80.040218] ata1.00: cmd 61/08:60:85:fa:f6/00:00:07:00:00/40 tag 12 ncq 4096 out
[   80.040218]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040220] ata1.00: status: { DRDY }
[   80.040223] ata1.00: cmd 61/28:68:dd:20:f7/00:00:07:00:00/40 tag 13 ncq 20480 out
[   80.040224]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040226] ata1.00: status: { DRDY }
[   80.040228] ata1.00: cmd 61/08:70:0d:21:f7/00:00:07:00:00/40 tag 14 ncq 4096 out
[   80.040229]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040231] ata1.00: status: { DRDY }
[   80.040234] ata1.00: cmd 61/08:78:fd:44:d3/00:00:07:00:00/40 tag 15 ncq 4096 out
[   80.040235]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040236] ata1.00: status: { DRDY }
[   80.040239] ata1.00: cmd 61/08:80:6d:1d:f8/00:00:07:00:00/40 tag 16 ncq 4096 out
[   80.040240]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040242] ata1.00: status: { DRDY }
[   80.040244] ata1.00: cmd 61/08:88:75:21:f8/00:00:07:00:00/40 tag 17 ncq 4096 out
[   80.040245]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040247] ata1.00: status: { DRDY }
[   80.040250] ata1.00: cmd 61/08:90:c5:b5:f8/00:00:07:00:00/40 tag 18 ncq 4096 out
[   80.040251]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040252] ata1.00: status: { DRDY }
[   80.040255] ata1.00: cmd 61/08:98:dd:21:f9/00:00:07:00:00/40 tag 19 ncq 4096 out
[   80.040256]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040258] ata1.00: status: { DRDY }
[   80.040260] ata1.00: cmd 61/10:a0:ed:f1:fa/00:00:07:00:00/40 tag 20 ncq 8192 out
[   80.040261]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040263] ata1.00: status: { DRDY }
[   80.040266] ata1.00: cmd 61/08:a8:bd:64:f8/00:00:07:00:00/40 tag 21 ncq 4096 out
[   80.040266]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040268] ata1.00: status: { DRDY }
[   80.040271] ata1.00: cmd 61/10:b0:c5:20:62/00:00:07:00:00/40 tag 22 ncq 8192 out
[   80.040272]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040274] ata1.00: status: { DRDY }
[   80.040276] ata1.00: cmd 61/08:b8:15:21:62/00:00:07:00:00/40 tag 23 ncq 4096 out
[   80.040277]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040279] ata1.00: status: { DRDY }
[   80.040282] ata1.00: cmd 61/08:c0:2d:21:62/00:00:07:00:00/40 tag 24 ncq 4096 out
[   80.040282]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040284] ata1.00: status: { DRDY }
[   80.040287] ata1.00: cmd 61/08:c8:bd:20:65/00:00:07:00:00/40 tag 25 ncq 4096 out
[   80.040288]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040289] ata1.00: status: { DRDY }
[   80.040292] ata1.00: cmd 61/08:d0:95:35:7e/00:00:07:00:00/40 tag 26 ncq 4096 out
[   80.040293]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040295] ata1.00: status: { DRDY }
[   80.040298] ata1.00: cmd 61/18:d8:bd:20:a6/00:00:07:00:00/40 tag 27 ncq 12288 out
[   80.040298]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040300] ata1.00: status: { DRDY }
[   80.040303] ata1.00: cmd 61/08:e0:e5:20:a6/00:00:07:00:00/40 tag 28 ncq 4096 out
[   80.040304]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040305] ata1.00: status: { DRDY }
[   80.040308] ata1.00: cmd 61/08:e8:2d:67:a9/00:00:07:00:00/40 tag 29 ncq 4096 out
[   80.040309]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040311] ata1.00: status: { DRDY }
[   80.040314] ata1.00: cmd 61/08:f0:35:67:a9/00:00:07:00:00/40 tag 30 ncq 4096 out
[   80.040315]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[   80.040316] ata1.00: status: { DRDY }
[   80.040319] ata1: hard resetting link
[   80.390127] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
[   80.394062] ata1.00: _GTF unexpected object type 0x1
[   80.401513] ata1.00: _GTF unexpected object type 0x1
[   80.403336] ata1.00: configured for UDMA/133
[   80.403407] ata1: EH complete
[   80.405473] sd 0:0:0:0: [sda] 488397168 512-byte hardware sectors: (250 GB/232 GiB)
[   80.405556] sd 0:0:0:0: [sda] Write Protect is off
[   80.405557] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
[   80.405799] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA



00:1f.1 IDE interface: Intel Corporation 82801HBM/HEM (ICH8M/ICH8M-E) IDE Controller (rev 03) (prog-if 8a [Master SecP PriP])
	Subsystem: Dell Device 0275
	Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap- 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin A routed to IRQ 18
	Region 0: I/O ports at 01f0 [size=8]
	Region 1: I/O ports at 03f4 [size=1]
	Region 2: I/O ports at 0170 [size=8]
	Region 3: I/O ports at 0374 [size=1]
	Region 4: I/O ports at 18a0 [size=16]
	Kernel driver in use: ata_piix

00:1f.2 SATA controller: Intel Corporation 82801HBM/HEM (ICH8M/ICH8M-E) SATA AHCI Controller (rev 03) (prog-if 01)
	Subsystem: Dell Device 0275
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
	Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin B routed to IRQ 2298
	Region 0: I/O ports at 18d8 [size=8]
	Region 1: I/O ports at 18cc [size=4]
	Region 2: I/O ports at 18d0 [size=8]
	Region 3: I/O ports at 18c8 [size=4]
	Region 4: I/O ports at 18e0 [size=32]
	Region 5: Memory at f8304000 (32-bit, non-prefetchable) [size=2K]
	Capabilities: [80] Message Signalled Interrupts: Mask- 64bit- Queue=0/2 Enable+
		Address: fee0300c  Data: 4191
	Capabilities: [70] Power Management version 3
		Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot+,D3cold-)
		Status: D0 PME-Enable- DSel=0 DScale=0 PME-
	Capabilities: [a8] SATA HBA <?>
	Kernel driver in use: ahci