Hi,
I just upgraded to 2.6.8 because I've had this same problem for while already. My machine suddenly starts lagging and /dev/hde stops working after that. I get something like this with dmesg:

Disabling IRQ #11
EXT3-fs error (device hde1): ext3_get_inode_loc: unable to read inode block - inode=7897448, block=15794189
end_request: I/O error, dev hde, sector 126353559
irq 11: nobody cared!
Stack pointer is garbage, not printing trace
handlers:
[] (ide_intr+0x0/0x18e)
[] (ohci_irq_handler+0x0/0x80e)
[] (usb_hcd_irq+0x0/0x67)
Disabling IRQ #11
EXT3-fs error (device hde1): ext3_get_inode_loc: unable to read inode block - inode=7897407, block=15794187
Debug: sleeping function called from invalid context at include/asm/semaphore.h:119
in_atomic():1, irqs_disabled():0
[] __might_sleep+0xb2/0xd3
[] drm_free+0xb7/0x150 [fglrx]
[] __ke_down_struct_sem+0x2a/0x44 [fglrx]
[] firegl_remove_all_drawables+0x3f/0x100 [fglrx]
[] firegl_release_helper+0x546/0x750 [fglrx]
[] firegl_takedown+0x32/0xaa0 [fglrx]
[] firegl_release+0x12f/0x190 [fglrx]
[] sys_fstat64+0x37/0x39
[] __fput+0x112/0x124
[] filp_close+0x59/0x86
[] sys_close+0x63/0x96
[] syscall_call+0x7/0xb
end_request: I/O error, dev hde, sector 4287
Buffer I/O error on device hde1, logical block 528
lost page write due to I/O error on hde1
irq 11: nobody cared!
Stack pointer is garbage, not printing trace
handlers:
[] (ide_intr+0x0/0x18e)
[] (ohci_irq_handler+0x0/0x80e)
[] (usb_hcd_irq+0x0/0x67)
Disabling IRQ #11
irq 11: nobody cared!
Stack pointer is garbage, not printing trace
handlers:
[] (ide_intr+0x0/0x18e)
[] (ohci_irq_handler+0x0/0x80e)
[] (usb_hcd_irq+0x0/0x67)
Disabling IRQ #11


On boot I get something like this

hde: sata_error = 0x00090000, watchdog = 1, siimage_mmio_ide_dma_test_irq
ieee1394: Host added: ID:BUS[0-00:1023] GUID[0004610000052c50]
hde: dma_timer_expiry: dma status == 0x61
hde: DMA timeout error
hde: dma timeout error: status=0xd0 { Busy }

hde: DMA disabled
ide2: reset phy, status=0x00000113, siimage_reset
ide2: reset timed-out, status=0xd0
hde: status timeout: status=0xd0 { Busy }

ide2: reset phy, status=0x00000113, siimage_reset
hde: drive not ready for command
irq 11: nobody cared!
[] __report_bad_irq+0x2a/0x8b
[] note_interrupt+0x6f/0x9f
[] do_IRQ+0x17c/0x1a8
[] common_interrupt+0x18/0x20
[] __do_softirq+0x2f/0x80
[] do_softirq+0x43/0x52
=======================
[] do_IRQ+0x155/0x1a8
[] common_interrupt+0x18/0x20
[] default_idle+0x23/0x26
[] cpu_idle+0x2c/0x35
[] start_kernel+0x165/0x17f
[] unknown_bootoption+0x0/0x149
handlers:
[] (ide_intr+0x0/0x18e)
[] (ohci_irq_handler+0x0/0x80e)
[] (usb_hcd_irq+0x0/0x67)
Disabling IRQ #11
ide2: reset phy dead, status=0x00000000
ide2: host reset_poll failure for hde.
hde: status timeout: status=0xd0 { Busy }

ide2: reset phy, status=0x00000000, siimage_reset
ide2: reset phy dead, status=0x00000000
hde: drive not ready for command
irq 11: nobody cared!
[] __report_bad_irq+0x2a/0x8b
[] note_interrupt+0x6f/0x9f
[] do_IRQ+0x17c/0x1a8
[] reset_pollfunc+0x0/0x1b9
[] common_interrupt+0x18/0x20
[] reset_pollfunc+0x0/0x1b9
[] ide_timer_expiry+0x118/0x220
[] ide_timer_expiry+0x0/0x220
[] run_timer_softirq+0xce/0x1ae
[] __do_softirq+0x7e/0x80
[] do_softirq+0x43/0x52
=======================
[] do_IRQ+0x155/0x1a8
[] common_interrupt+0x18/0x20
[] default_idle+0x23/0x26
[] cpu_idle+0x2c/0x35
[] start_kernel+0x165/0x17f
[] unknown_bootoption+0x0/0x149
handlers:
[] (ide_intr+0x0/0x18e)
[] (ohci_irq_handler+0x0/0x80e)
[] (usb_hcd_irq+0x0/0x67)
Disabling IRQ #11
ide2: reset phy dead, status=0x00000000
ide2: host reset_poll failure for hde.
end_request: I/O error, dev hde, sector 65
irq 11: nobody cared!
[] __report_bad_irq+0x2a/0x8b
[] note_interrupt+0x6f/0x9f
[] do_IRQ+0x17c/0x1a8
[] reset_pollfunc+0x0/0x1b9
[] common_interrupt+0x18/0x20
[] reset_pollfunc+0x0/0x1b9
[] ide_timer_expiry+0x118/0x220
[] ide_timer_expiry+0x0/0x220
[] run_timer_softirq+0xce/0x1ae
[] __do_softirq+0x7e/0x80
[] do_softirq+0x43/0x52
=======================
[] do_IRQ+0x155/0x1a8
[] common_interrupt+0x18/0x20
[] default_idle+0x23/0x26
[] cpu_idle+0x2c/0x35
[] start_kernel+0x165/0x17f
[] unknown_bootoption+0x0/0x149
handlers:
[] (ide_intr+0x0/0x18e)
[] (ohci_irq_handler+0x0/0x80e)
[] (usb_hcd_irq+0x0/0x67)
Disabling IRQ #11
EXT3-fs: unable to read superblock
irq 11: nobody cared!
Stack pointer is garbage, not printing trace
handlers:
[] (ide_intr+0x0/0x18e)
[] (ohci_irq_handler+0x0/0x80e)
[] (usb_hcd_irq+0x0/0x67)
Disabling IRQ #11
irq 11: nobody cared!
Stack pointer is garbage, not printing trace
handlers:
[] (ide_intr+0x0/0x18e)
[] (ohci_irq_handler+0x0/0x80e)
[] (usb_hcd_irq+0x0/0x67)
Disabling IRQ #11

Sorry for long post, I would have dmesg to my homepage but all my passwords are in /dev/hde and I can't access them now. My motherboard is EPOX 8rda3+