[Archive] User Preferences Java Error?

Message by T.:
I’ve been using SPIS/UI, and things seemed to be working fine (running several simulations over the course of the day), then I started getting this message in the terminal:
java.util.prefs.FileSystemPreferences syncWorld
WARNING: Couldn’t flush user prefs: java.util.prefs.BackingStoreException: Couldn’t get file lock.
Now the simulations don’t start, and the app crashes.
Any ideas?

Message by T.:
Figured it out. I had two SPIS run accessing the same files (I think). When I killed the other one the error went away!