New data point. I've tried a lockdebug kernel but got no lockdebug 
messages.

Furthermore, i've tried out that in the other console `ls' works but
`ls -al' locks up as described so i suspect `stat' is to blame? or is that 
for NFS communication needs to be done and it blocks on a mutex?

When i `synced' in KDB i allways get a kernel supervisor trap poage fault 
code 0 when unmounting the offending NFS mount. The kernel traceback is 
pretty long but that could be due to the break-in.