(no subject)

Hello Community,
I hope someone could help me with this problem. The last days I have tried to find a solution, but haven't found one.
The watchdog timeout happens, when I'm going to download something or copy a file on my FTP server. When I start the transfer of the file, I wait a moment and then my down-/upload freezes at something around 500[ ]KB. After waiting a little while or press a key like "return", it comes to the interrupt storm.

interrupt storm detected on "irq51:"; throttling interrupt source

Here is some information about my system:
ifconfig msk0
msk0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500	options=c009b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,VLAN_HWTSO,LINKSTATE>	ether bc:ae:c5:5a:ef:ec	inet 192.168.2.30 netmask 0xffffff00 broadcast 192.168.2.255 	nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>	media: Ethernet autoselect (100baseTX <full-duplex,flowcontrol,rxpause,txpause>)	status: active

pciconf -lv
mskc0_at_pci0:3:0:0:	class=0x020000 card=0x84391043 chip=0x438111ab rev=0x11 hdr=0x00    vendor     = 'Marvell Technology Group Ltd.'    device     = 'Yukon Optima 88E8059 [PCIe Gigabit Ethernet Controller with AVB]'    class      = network    subclass   = ethernet

vmstat -i
interrupt                          total       rateirq1: atkbd0                         916          2irq16: hdac1                          97          0irq17: ehci0 ehci1+                 8729         21irq18: ohci0 ohci1*                   67          0irq19: ahci1                        2883          7irq25: hdac0                           4          0irq51: mskc0                          90          0irq256: hpet0:t0                   30332         75Total                              43118        107

loader.conf
hw.msk.msi_disable=1hw.pci.enable_msi=0hw.pci.enable_msix=0rc.confCode:hostname="FreeBSD.local.domain"keymap="german.iso.acc.kbd"ifconfig_msk0="DHCP"
sshd_enable="YES"moused_enable="YES"powerd_enable="YES"# Set dumpdev to "AUTO" to enable crash dumps, "NO" to disabledumpdev="AUTO"

I have also tried to change ifconfig_msk0="DHCP" to ifconfig_msk0="SYNCDHCP" but nothing changed.
If nothing helps, I will buy a new network card.