problem with UDMA mode on XP1000

[Riccardo.Veraldi at fi.infn.it]

hello,
FreeBSD-4.8, XP1000.
I installed a FAStrak 100:

atapci2: <Promise TX2 ATA100 controller> port
0x1010-0x101f,0x1034-0x1037,0x1028-0x102f,0x1030-0x1033,0x1020-0x1027 mem
0x1020000-0x102ffff irq 32 at device 13.0 on pci0

and I Attached a UDMA disk:

ad0: 38172MB <QUANTUM FIREBALLP AS40.0> [77557/16/63] at ata3-master
UDMA100

the problem is that I got often these messages:

ad0: UDMA ICRC error reading fsbn 78177393 of 0-3 (ad0 bn 78177393; cn
77556 tn 15 sn 0) retrying

and often it reverts to PIO mode...

anyone has hints how I could fix this problem?
could it be given by the fact that I isntalled the PCI card on the 64-bit
slot?
thanks

Rick