Just installed IDEA 8975, JDK 1.6.0_10, Ubuntu 8.04.
Changed to settings (File/Settings) are being ignored. In the Settings dialog, the Apply button remains disabled regardless of which settings are changed. Clicking OK closes the dialog without any error, but on re-opening the old settings are still in-place.
Found this while trying to disable smooth scrolling--nice effect, just a little slow for my tastes. But other settings changes are ignored as well.
No errors in idea.log.