My desktop is experiencing issues with DMA lately.  This has been going 
on with the 2.6.8-rcX releases IIRC.  I'm currently on rc3.  The 
hardware is all brand new.

Scott ~ # hdparm -i /dev/hda

/dev/hda:

 Model=SAMSUNG SP1614N, FwRev=TM100-23, SerialNo=0642J1FW704776
 Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs }
 RawCHS=16383/16/63, TrkSize=34902, SectSize=554, ECCbytes=4
 BuffType=DualPortCache, BuffSize=8192kB, MaxMultSect=16, MultSect=16
 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=268435455
 IORDY=on/off, tPIO={min:240,w/IORDY:120}, tDMA={min:120,rec:120}
 PIO modes:  pio0 pio1 pio2 pio3 pio4
 DMA modes:  mdma0 mdma1 mdma2
 UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5
 AdvancedPM=no WriteCache=enabled
 Drive conforms to: (null):

Scott ~ # lspci
0000:00:00.0 Host bridge: VIA Technologies, Inc. VT8385 [K8T800 AGP] 
Host Bridge (rev 01)
0000:00:01.0 PCI bridge: VIA Technologies, Inc. VT8237 PCI bridge 
[K8T800 South]
0000:00:07.0 FireWire (IEEE 1394): VIA Technologies, Inc. IEEE 1394 Host 
Controller (rev 80)
0000:00:08.0 RAID bus controller: Promise Technology, Inc. PDC20378 
(FastTrak 378/SATA 378) (rev 02)
0000:00:09.0 SCSI storage controller: LSI Logic / Symbios Logic 53c875J 
(rev 04)
0000:00:0a.0 Ethernet controller: 3Com Corporation 3c940 
10/100/1000Base-T [Marvell] (rev 12)
0000:00:0c.0 Communication controller: Conexant HCF 56k Data/Fax Modem 
(rev 08)
0000:00:0d.0 Ethernet controller: Lite-On Communications Inc LNE100TX 
(rev 20)
0000:00:0f.0 RAID bus controller: VIA Technologies, Inc. VIA VT6420 SATA 
RAID Controller (rev 80)
0000:00:0f.1 IDE interface: VIA Technologies, Inc. 
VT82C586A/B/VT82C686/A/B/VT823x/A/C PIPC Bus Master IDE (rev 06)
0000:00:10.0 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 
1.1 Controller (rev 81)
0000:00:10.1 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 
1.1 Controller (rev 81)
0000:00:10.2 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 
1.1 Controller (rev 81)
0000:00:10.3 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 
1.1 Controller (rev 81)
0000:00:10.4 USB Controller: VIA Technologies, Inc. USB 2.0 (rev 86)
0000:00:11.0 ISA bridge: VIA Technologies, Inc. VT8237 ISA bridge 
[K8T800 South]
0000:00:11.5 Multimedia audio controller: VIA Technologies, Inc. 
VT8233/A/8235/8237 AC97 Audio Controller (rev 60)
0000:00:18.0 Host bridge: Advanced Micro Devices [AMD] K8 NorthBridge
0000:00:18.1 Host bridge: Advanced Micro Devices [AMD] K8 NorthBridge
0000:00:18.2 Host bridge: Advanced Micro Devices [AMD] K8 NorthBridge
0000:00:18.3 Host bridge: Advanced Micro Devices [AMD] K8 NorthBridge
0000:01:00.0 VGA compatible controller: nVidia Corporation NV34 [GeForce 
FX 5200] (rev a1)


hda: dma_timer_expiry: dma status == 0x24
hda: DMA interrupt recovery
hda: lost interrupt
hdd: irq timeout: status=0x80 { Busy }
hdd: irq timeout: error=0x00
hdd: DMA disabled
hdd: ATAPI reset complete
hda: dma_timer_expiry: dma status == 0x24
hda: DMA interrupt recovery
hda: lost interrupt
hda: dma_timer_expiry: dma status == 0x24
hda: DMA interrupt recovery
hda: lost interrupt
hda: dma_timer_expiry: dma status == 0x24
hda: DMA interrupt recovery
hda: lost interrupt
hda: dma_timer_expiry: dma status == 0x24
hda: DMA interrupt recovery
hda: lost interrupt
hda: dma_timer_expiry: dma status == 0x24
hda: DMA interrupt recovery
hda: lost interrupt
hda: dma_timer_expiry: dma status == 0x24
hda: DMA interrupt recovery
hda: lost interrupt