I could solve the problem: it was caused by a compact-flash wireless card 
in a pcmcia-adapter (that runs without problems on other devices). So
changing the card let me succesfully compile packages. 

Soon I will put them on my webhoster's server and post a link here 
for download. 

Have a nice start in 2008 everybody
Wolfgang

At Wed, 26 Dec 2007 15:00:34 +0100,
netbsd  wrote:
> 
> 
> 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