Weird wifi behavior

Hello all.
First of all, I'm not on current, but on stable:

FreeBSD pcbsd-6648 9.0-STABLE FreeBSD 9.0-STABLE #8: Fri May 18
16:12:29 UTC 2012
root_at_build9x64.pcbsd.org:/usr/obj/builds/i386/pcbsd-build90/fbsd-source/9.0/sys/GENERIC
 i386

I have lenovo s10-2 (which is have some unsupported broadcom wifi).
I did replace wifi with
ath0: <Atheros 5424/2424> mem 0x56100000-0x5610ffff irq 17 at device 0.0 on pci2
ath0: AR2425 mac 14.2 RF5424 phy 7.0


And weirdness begin.
At my home I have wifi router in WEP mode. All devices/laptops are
working just fine. But s10-2 is somehow get broken packets;
fetch - got broken downloads (incorrect MD5, and sometimes say to me
that length of file is invalid);
wget - stops, saying something about MAC error.
ssh - works fine while I simply use console (cd, ls) - can lasts
hours.but! If I run mc, and starts something like copy/delete files
(which heavily updates screen) - ssh drops connections with message
packet error.
browsing - pretty working (but not file downloads of course).

At my workplace we using WPA with password. At work I can download
packages,files,etc - all is OK with fine checksums.
I happen to note this while testing PC-BSD 9.0, currently I'm on
latest PC-BSD beta.

Any thoughts/advices on how to test it/fix it?
I'd gladly use broadcom (bcm94312MCG) if it works. BTW, maybe someone
could mentor me on developing/porting driver? :)

-- 
Regards,
Alexander Yerenkow