It is working! (two days) I have modified the bios settings to "reserve" the irq 9 and now all the ethernet irqs are dispatched to irq 11. I don't know why the irq 9 "is bad" for the "Intel PRO/1000MT Dual Port Server Adapter" (but with Linux 2.6.18 it works). Thanks to all for the suggestions...
-Massimiliano this is the new dmesg: OpenBSD 4.2 (GENERIC) #375: Tue Aug 28 10:38:44 MDT 2007 [EMAIL PROTECTED]:/usr/src/sys/arch/i386/compile/GENERIC cpu0: VIA Samuel 2 ("CentaurHauls" 686-class) 602 MHz cpu0: FPU,DE,TSC,MSR,MTRR,PGE,MMX real mem = 519598080 (495MB) avail mem = 494751744 (471MB) mainbus0 at root bios0 at mainbus0: AT/286+ BIOS, date 03/11/04, BIOS32 rev. 0 @ 0xface0, SMBIOS rev. 2.2 @ 0xf0800 (26 entries) bios0: vendor Award Software International, Inc. version "6.00 PG" date 03/11/2004 bios0: VIA Technologies, Inc. VT8623-8235 apm0 at bios0: Power Management spec V1.2 apm0: AC on, battery charge unknown apm0: flags 70102 dobusy 1 doidle 1 pcibios0 at bios0: rev 2.1 @ 0xf0000/0xdba4 pcibios0: PCI IRQ Routing Table rev 1.0 @ 0xfdb10/144 (7 entries) pcibios0: PCI Exclusive IRQs: 11 pcibios0: PCI Interrupt Router at 000:17:0 ("VIA VT82C596A ISA" rev 0x00) pcibios0: PCI bus #1 is the last bus bios0: ROM list: 0xc0000/0xe000 cpu0 at mainbus0 pci0 at mainbus0 bus 0: configuration mode 1 (no bios) pchb0 at pci0 dev 0 function 0 "VIA VT8623 PCI" rev 0x00 ppb0 at pci0 dev 1 function 0 "VIA VT8633 AGP" rev 0x00 pci1 at ppb0 bus 1 vga1 at pci1 dev 0 function 0 "VIA CLE266" rev 0x03: aperture at 0xe0000000, size 0x10000000 wsdisplay0 at vga1 mux 1: console (80x25, vt100 emulation) wsdisplay0: screen 1-5 added (80x25, vt100 emulation) vr0 at pci0 dev 15 function 0 "VIA VT6105 RhineIII" rev 0x8b: irq 11, address 00:40:63:de:4f:6c ukphy0 at vr0 phy 1: Generic IEEE 802.3u media interface, rev. 9: OUI 0x004063, model 0x0034 uhci0 at pci0 dev 16 function 0 "VIA VT83C572 USB" rev 0x80: irq 11 uhci1 at pci0 dev 16 function 1 "VIA VT83C572 USB" rev 0x80: irq 11 uhci2 at pci0 dev 16 function 2 "VIA VT83C572 USB" rev 0x80: irq 11 ehci0 at pci0 dev 16 function 3 "VIA VT6202 USB" rev 0x82: irq 11 usb0 at ehci0: USB revision 2.0 uhub0 at usb0: VIA EHCI root hub, rev 2.00/1.00, addr 1 viapm0 at pci0 dev 17 function 0 "VIA VT8235 ISA" rev 0x00 iic0 at viapm0 pciide0 at pci0 dev 17 function 1 "VIA VT82C571 IDE" rev 0x06: ATA133, channel 0 configured to compatibility, channel 1 configured to co mpatibility wd0 at pciide0 channel 0 drive 0: <HTS721080G9AT00> wd0: 16-sector PIO, LBA48, 76319MB, 156301488 sectors wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 5 atapiscsi0 at pciide0 channel 1 drive 0 scsibus0 at atapiscsi0: 2 targets cd0 at scsibus0 targ 0 lun 0: <HL-DT-ST, DVD-ROM GDR8082N, 0B11> SCSI0 5/cdrom removable cd0(pciide0:1:0): using PIO mode 4, Ultra-DMA mode 2 vr1 at pci0 dev 18 function 0 "VIA RhineII-2" rev 0x74: irq 11, address 00:40:63:de:4f:8a ukphy1 at vr1 phy 1: Generic IEEE 802.3u media interface, rev. 10: OUI 0x004063, model 0x0032 em0 at pci0 dev 19 function 0 "Intel PRO/1000MT (82546EB)" rev 0x01: irq 11, address 00:07:e9:1f:9f:46 em1 at pci0 dev 19 function 1 "Intel PRO/1000MT (82546EB)" rev 0x01: irq 11, address 00:07:e9:1f:9f:47 usb1 at uhci0: USB revision 1.0 uhub1 at usb1: VIA UHCI root hub, rev 1.00/1.00, addr 1 usb2 at uhci1: USB revision 1.0 uhub2 at usb2: VIA UHCI root hub, rev 1.00/1.00, addr 1 usb3 at uhci2: USB revision 1.0 uhub3 at usb3: VIA UHCI root hub, rev 1.00/1.00, addr 1 isa0 at mainbus0 isadma0 at isa0 pckbc0 at isa0 port 0x60/5 pckbd0 at pckbc0 (kbd slot) pckbc0: using irq 1 for kbd slot wskbd0 at pckbd0: console keyboard, using wsdisplay0 pmsi0 at pckbc0 (aux slot) pckbc0: using irq 12 for aux slot wsmouse0 at pmsi0 mux 0 pcppi0 at isa0 port 0x61 midi0 at pcppi0: <PC speaker> spkr0 at pcppi0 lpt0 at isa0 port 0x378/4 irq 7 viasio0 at isa0 port 0x2e/2: VT1211 rev 0x02, HM, WDG not activated viasio1 at isa0 port 0x4e/2: VT1211 rev 0x02, HM not activated, WDG not activated npx0 at isa0 port 0xf0/16: reported by CPUID; using exception 16 pccom0 at isa0 port 0x3f8/8 irq 4: ns16550a, 16 byte fifo pccom1 at isa0 port 0x2f8/8 irq 3: ns16550a, 16 byte fifo pccom2 at isa0 port 0x3e8/8 irq 5: ns16550a, 16 byte fifo biomask ef45 netmask ef45 ttymask ffc7 pctr: user-level cycle counter enabled dkcsum: wd0 matches BIOS drive 0x80 root on wd0a swap on wd0b dump on wd0b wd0a: aborted command, interface CRC error reading fsbn 403040 of 403040-403071 (wd0 bn 79041215; cn 4920 tn 22 sn 29), retrying wd0: soft error (corrected) wd0: transfer error, downgrading to Ultra-DMA mode 4 wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 4 wd0a: aborted command, interface CRC error reading fsbn 138080 of 138080-138111 (wd0 bn 78776255; cn 4903 tn 151 sn 47), retrying wd0: soft error (corrected)