Perhaps close Maya.
Delete the preferences folder (upon restart Maya will recreate it)
If it won't let you delete it, you can
(1) Reboot and perhaps start in safe-mode (but should be fine after a reboot)
(2) Use "Unlocker" to unlock it so you can delete it,
http://ccollomb.free.fr/unlocker/
There are a few different ways. If you don't mind losing your preferences, then just delete the folder and it'll reset.