xscreensaver problems

[Bruno Costacurta]

Hello,
I have randoms problems with xscreensaver (please see hereafter output)
Versions are:
-package = xscreensaver-base-4.21-4
-Fedora = FC4

(...)
xscreensaver couldn't grab keyboard (AlreadyGrabbed)
Unknown argument : -root
ant [options] ...
(...)
xscreensaver : 0 : child pid 17066 (ant) exited abnormally (code 1)
(...)

Thanks for any clue,
Bruno