Sid X.Org going crazy

A few apt-get update's ago, my X.Org server suddenly stopped working properly with my keyboard. Kb still worked fine in pure console, but when I typed anything in X my kb scroll lock led was turned on and off as I typed, making it impossible to write properly. Also, it was like the Ctrl key was costantly kept pushed.

The errors I got were only of this kind:
expected keysym, got ISO_Level5_Shift: line 17 of level5
expected keysym, got ISO_Level5_Shift: line 23 of level5
expected keysym, got ISO_Level5_Latch: line 27 of level5
expected keysym, got ISO_Level5_Latch: line 32 of level5
expected keysym, got ISO_Level5_Lock: line 36 of level5
expected keysym, got ISO_Level5_Lock: line 41 of level5
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Warning: Multiple interpretations of "NoSymbol+AnyOfOrNone(all)"
> Using last definition for duplicate fields
> Warning: Multiple interpretations of "NoSymbol+AnyOf(all)"
> Using last definition for duplicate fields
> Warning: Multiple interpretations of "NoSymbol+AnyOfOrNone(all)"
> Using last definition for duplicate fields
Errors from xkbcomp are not fatal to the X server
expected keysym, got ISO_Level5_Shift: line 17 of level5
expected keysym, got ISO_Level5_Shift: line 23 of level5
expected keysym, got ISO_Level5_Latch: line 27 of level5
expected keysym, got ISO_Level5_Latch: line 32 of level5
expected keysym, got ISO_Level5_Lock: line 36 of level5
expected keysym, got ISO_Level5_Lock: line 41 of level5
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Warning: Multiple interpretations of "NoSymbol+AnyOfOrNone(all)"
> Using last definition for duplicate fields
> Warning: Multiple interpretations of "NoSymbol+AnyOf(all)"
> Using last definition for duplicate fields
> Warning: Multiple interpretations of "NoSymbol+AnyOfOrNone(all)"
> Using last definition for duplicate fields
> Warning: Type "ONE_LEVEL" has 1 levels, but has 2 symbols
> Ignoring extra symbols
Errors from xkbcomp are not fatal to the X server

I finally got the situation manageable by configuring /etc/X11/xorg.conf this way:
Option "XkbRules" "walkaround"
#Option "XkbRules" "xorg"

Don't ask why, but now I can use my kb at 70%. I still get some errors, such as can't type letters with accents, @, £ and so on, plus, obviously, the following:
(EE) XKB: Couldn't open rules file /usr/share/X11/xkb/rules/xfree
(WW) Couldn't load XKB keymap, falling back to pre-XKB keymap
(EE) Error compiling keymap (server-0)
(EE) XKB: Couldn't compile keymap
SetClientVersion: 0 9
SetKbdSettings - type: 0 rate: 30 delay: 500 snumlk: 0

Finally, I found the bug filed on bdo:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=514975

Following its instructions, I upgraded libx11-6 from 1.0.3-7 to 1.1.5-2 and restored Option "XkbRules" "xorg" in xorg.conf. After restarting X and issuing setxkbmap it I can finally use my kb 100%. Yikes!