constant packagebuild fail

Hello,
I'm new to running NetBSD (3.1) on a Jornade 720.
I downloaded and installed the 3.1 Sets, it works. Then
I set up a nfs-connection to my pc, also running NetBSD 3.1.
In the nfs-mounted directory is pkgsrc and a swap-file that is
used by the jornada.

Whenever I try to build a package, it ends with an error message, 
that says:

(time)ETA panic: kernel diagnostic assertion "sc->_txcmds > 0" failed: file "/home/builds/ab/netbsd-3-1-RELEASE/src/sys/dev/ic/wi.c", line 1749
Stopped in pid 4847.1 (ftp) at 0xc01ecbec:    mov   r15, r14


So because whatever I try to build the same message appears, 
I would like to ask, if somebody knows, where the problem is 
and how to fix it. Still there are no precompiled packages to 
be found, so untill now I have a running NetBSD-Jornada including X,
but no programs.


Thanks in advance for help
and a happy new year,
Wolfgang