does journaling cause DMA-WRITE failure?

[s m]

hello all,

i have freebsd8.2 on my system with journaled gpt partitions. occasionally,
i see the below errors in startup and system doesn't boot correctly. if i
restart system, it boot normally and every thing is ok.
these errors are:
ad3: WARNING - WRITE_DMA requeued  due to channel reset LBA=635411
ad3: WARNING - READ_DMA requeued  due to channel reset LBA=635411
ata1: FAILURE - already active DMA on this device
ata1: setting up DMA failed
ad3: WARNING - WRITE_DMA requeued  due to channel reset LBA=635411
ata1: FAILURE - already active DMA on this device

and these errors are shown repeatedly.

i have two question: does journaling cause to happen these errors? and if i
set hw.ata.ata_dma to 0, is it resolve the problem? if yes, has it any side
effect or not?

any comments or hints are really appreciated.
SAM