problems with sil3512 on freebsd 6.1

[Patrick Georgi]

Hi,
(please CC me, I'm not subscribed)

I'm currently working on a freebsd box I've inherited from the former admin, and been tasked with
installing new hard disks on sata.
Currently, it has a scsi disk containing the system and an ide disk containing the data partitions
(it's a file server).

While I managed to access the sata disks, and set up a geom mirror on it, it's highly unstable, and
crashes reliably when accessing the sata disks if there is load on network or the ide bus. it's
relatively stable if only sata is accessed.
The sata controller in use hosts a sil3512 chipset. disabling dma via hw.ata.ata_dma doesn't help.

Any ideas if that chip is known to have such problems (despite being listed on ata(4))? Any things
I could try to get it to work, eg. updating, other settings?

Thanks in advance,
Patrick Georgi