I've just faced an interesting bug. I tried to use user.home for saving path; The thing is the user.home in win xp is starting with
X:\Documents and Settings\
... sure the spaces take their place. The exception says
java.io.FileNotFoundException: C:\Documents%20and%20Settings ...
... so, as I can see, all spaces are replaced with '%'; I suppose it is an encoding problem but I am not pretty sure. The bug "5077403" page doesn't provide any work around; But I hope there should be some?