wi0 down when print a lot of data to screen over ssh

[Ren Zhen]

wi0 goes down when I run a program print a lot of data to
stdout, or when I use zmrx-zmtx it also goes down.

kernel says:
kernel: wi0: timeout in wi_seek to 152/0
last message repeated 7 times
kernel: wi0: device timeout
kernel: wi0: timeout in wi_seek to 152/0
kernel: wi0: link state changed to DOWN

another time kernel says:
kernel: wi0: timeout in wi_cmd 0x010b; event status 0x8000
kernel: wi0: xmit failed
kernel: wi0: timeout in wi_seek to 128/0
last message repeated 3 times

System Information:
FreeBSD 6.1-STABLE
IBM ThinkPad T23-4NC with a 802.11b wifi card original.
wi0 use WEP 128bit encryption

My Kernel configuration:
machine i386
cpu I686_CPU
ident BKCNG

options SCHED_4BSD # 4BSD scheduler
options PREEMPTION # Enable kernel thread preemption
options INET # InterNETworking
options INET6 # IPv6 communications protocols
options FFS # Berkeley Fast Filesystem
options SOFTUPDATES # Enable FFS soft updates support
options UFS_ACL # Support for access control lists
options UFS_DIRHASH # Improve performance on big directories
options MD_ROOT # MD is a potential root device
options NFSCLIENT # Network Filesystem Client
options NFSSERVER # Network Filesystem Server
options NFS_ROOT # NFS usable as /, requires NFSCLIENT
options MSDOSFS # MSDOS Filesystem
options CD9660 # ISO 9660 Filesystem
options NTFS
options PROCFS # Process filesystem (requires PSEUDOFS)
options PSEUDOFS # Pseudo-filesystem framework
options GEOM_GPT # GUID Partition Tables.
options COMPAT_43 # Compatible with BSD 4.3 [KEEP THIS!]
options COMPAT_FREEBSD4 # Compatible with FreeBSD4
options COMPAT_FREEBSD5 # Compatible with FreeBSD5
options SCSI_DELAY=5000 # Delay (in ms) before probing SCSI
options KTRACE # ktrace(1) support
options SYSVSHM # SYSV-style shared memory
options SYSVMSG # SYSV-style message queues
options SYSVSEM # SYSV-style semaphores
options _KPOSIX_PRIORITY_SCHEDULING # POSIX P1003_1B real-time extensions
options KBD_INSTALL_CDEV # install a CDEV entry in /dev
options AHC_REG_PRETTY_PRINT # Print register bitfields in debug
options AHD_REG_PRETTY_PRINT # Print register bitfields in debug
options ADAPTIVE_GIANT # Giant mutex is adaptive.
device apic # I/O APIC

device eisa
device pci

device ata
device atadisk # ATA disk drives
device atapicd # ATAPI CDROM drives
options ATA_STATIC_ID # Static device numbering

device atkbdc # AT keyboard controller
device atkbd # AT keyboard
device psm # PS/2 mouse

device kbdmux # keyboard multiplexer

device vga # VGA video card driver
options VESA
device acpi
device acpi_ibm
#device acpi_video
device drm
device savagedrm
device splash # Splash screen and screen saver support

device sc
options SC_PIXEL_MODE
options VGA_WIDTH90

device agp # support several AGP chipsets

device pmtimer

device cbb # cardbus (yenta) bridge
device pccard # PC Card (16-bit) bus
device cardbus # CardBus (32-bit) bus

device sio # 8250, 16[45]50 based serial ports

device ppc
device ppbus # Parallel port bus (required)
device lpt # Printer

device sound
device snd_ich

device miibus # MII bus support
device fxp # Intel EtherExpress PRO/100B (82557, 82558)

device wlan # 802.11 support
device wi # WaveLAN/Intersil/Symbol 802.11 wireless NICs.
device wlan_wep

device loop # Network loopback
device random # Entropy device
device ether # Ethernet support
device sl # Kernel SLIP
device ppp # Kernel PPP
device tun # Packet tunnel.
device pty # Pseudo-ttys (telnet etc)
device md # Memory "disks"
device gif # IPv6 and IPv4 tunneling
device faith # IPv6-to-IPv4 relaying (translation)

device bpf # Berkeley packet filter

device uhci # UHCI PCI->USB interface
device ohci # OHCI PCI->USB interface
device ehci # EHCI PCI->USB interface (USB 2.0)
device usb # USB Bus (required)
device ugen # Generic
device uhid # "Human Interface Devices"
device ukbd # Keyboard
device umass # Disks/Mass storage - Requires scbus and da
device ums # Mouse


But, I use the sftp there is no problem. So, is the wi0 have a problem?