Do you have dual monitors? If yes, this can occur when using FAB 3000 and ACE 3000 across multiple screens (keep it on the original screen).
Our tools use a Linux based GUI toolkit, and unfortunately this is a known issue that occurs internally inside the Linux based GUI toolkit.
Quick Fix: When multiple monitors are available, open and run our software from the primary monitor (i.e first screen) and everything should appear fine.
Note: If FAB 3000 has worked fine before but now differently, maybe restoring the default settings will help,
Simon Garrison