6.0-RC1: ral(4) driver broken? network interruptions

Greetings,

I have an oldish computer VIA KT333/Athlon XP board (i386) that I
recently upgraded from FreeBSD 5.4 (was rock solid) to 6.0-BETA3 and
today to 6.0-RC1 (I rebuilt everything from scratch).

I had to upgrade because there was no ral(4) driver for FreeBSD 5.4 but
only for 6.0, which I needed after I had switched from 3C900 Combo
(802.3 whatever 10Base2) to Edimax EW-7128g (802.11b/g). The latter card
is based on RT2525 and RT2560 chips/modules. I'm using WPA-TKIP to
connect it to an AVM Fritz!Box Fon WLAN.

The computer is dual boot with SUSE Linux 9.3, where RA card is
absolutely stable and does 48 Mbps without trouble.

Booting FreeBSD 6.0-BETA3 or -RC1, I constantly see lines like these
from cvsup running on FreeBSD:

Parsing supfile "/usr/share/examples/cvsup/ports-supfile"
Connecting to cvsup7.de.FreeBSD.org
Connected to cvsup7.de.FreeBSD.org
Server software version: SNAP_16_1g
Negotiating file attribute support
Exchanging collection information
Establishing multiplexed-mode data connection
Running
TreeList failed: Network write failure: Connection closed
Will retry at 19:10:59

and in my ssh client (running on Linux, logging in to that FreeBSD
machine), with varying numbers:

Disconnecting: Bad packet length 3626208547.

Something in TKIP, WLAN or ral appears to be hosed. Anyone else seeing this?

-- 
Matthias Andree