using Fedora Core 2, fresh upgrade from a never-patched RedHat 9.
upon logging in to X in run-level 5 (or after 'startx' in run-level 3) I get a
series of identical warning dialogues reporting 'XKB Configuration Error'
'probably an internal xserver error.  Having cleared this dialogue, which
appears 5 or 6 times in series, everything appears to operate normally.
As requested by that dialogue, here is some debugging output:
$ xprop -root | grep XKB
_XKB_RULES_NAMES_BACKUP(STRING) = "xfree86", "pc105", "us", "", ""
_XKB_RULES_NAMES(STRING) = "xfree86", "pc105", "us", "", ""

$ gconftool-2 -R /desktop/gnome/peripherals/keyboard/xkb
 layouts = [us]
 model = pc105
 overrideSettings = false
 options = []

it might be of interest to note that, on a different system  which is a fresh
install of Fedora Core 2 on a fresh partition, this error dialogue occurs once
for every user except root but is the least of many (probably gnome
configuration) problems which make X/gnome unusable for those users.