Windows2000 pro or server
simplified chinese
merlin b90

run swingset2 demo, set it's L&F as windows, then lots of character are replace as space square.

Also, you can reproduce it using attached test case.
#tar -xvf swing_tests.tar
#cd swing\classes
#java SwingTest -resource resources zh

then set the L&F to windows, will get the picture like attachment.
You can also choose the UI's open menu, save menu etc, so many square box.

I have tried it on window98, NT and ME for sch and windows2000 pro ,server for traditional, all ok.