signal 10/11 on freebsd

Moin,

I use sfs 0.7.2 on a FreeBSD 4.10 server and connect to it from linux
clients. It works but after a day I have some messages like this in
the server log:

pid 17070 (fstat), uid 0: exited on signal 11
pid 18973 (fstat), uid 0: exited on signal 11
pid 56143 (fstat), uid 0: exited on signal 10

I know, signal 11 suggest a hardware error but if i disable the sfs
server  the messages go away. I also cant find a core dump on the
server. Now I run the server in debug mode under strace. Maybe I can
see something. In rare cases the server/client hangs if I transfer a
lot of bigger files but I didn't see a association with the "signal
10/11" messages.

Any hint?
Matthias