Walk Through Windows is Alt+Tab. Ctrl+Tab is Walk Through Desktops.

In any event, I can change the shortcut for both of them and it works.

What shortcut did you try?

ups, I ment Alt+TAB of course. If the shortcut for 'Walk Through Windows' is set to Alt+TAB a window list is shown once I press the shortcut. If I set the shortcut to anything else (e.g. Win+TAB, just TAB), switching winows works fine but the windowlist isn't displayed.

So Alt+Tab is the only shortcut that works?

hmm... I just rechecked it. 'Every' shortcut using Alt or Ctrl seems to work (tryed Alt+Shift+Tab, Alt+1, Ctrl+Tab, Ctrl+1). 'Every' shortcut using Win as meta key doesn't work (tryed Win+Tab, Win+1, Win+Shift+Tab). Shift+'a' is working where Shift+'4' (us layout '$') isn't.

maybe the winkey has been remapped to not work as meta key but similar to window$ (i do so to call the executor/the startmenu)
try xev to figure out

The winkeys produce Super_L|R this seems ok to me. Win+Tab is working fine (e.g. switching windows) but unlinke Alt+Tab the window list isn't shown.

Is this specific to the Walk though windows feature or do all shortcuts have this problem?

Waiting for a response.

I just ran into something similar, in KDE 3.5.2.

I created a new account, to make sure nothing got messed up.
I switched to the "KDE Default for 4 Modifier Keys" scheme.
Here, Win-Tab and Win-Shift-Tab are assigned to walk through desktops, forward and backwards.

Now, if I keep pressing Win-Tab, I only switch between 1st and 2nd desktops (or sometimes 1st and some other - the last desktop I visited?). If I press Win-Shift-Tab, it displays the list - though it is NOT supposed to (this is the shortcut to walking through desktops, not desktop list), never switches the desktop, and never hides the list.

If I instead assign Win-Tab and Win-Shift-Tab to the next two actions, walk through the desktop list, forward and reverse... The behavior is EXACTLY the same.

I looked at the output of xev - nothing interesting. I see "Super_L", which works like a modifier key, same as Alt, Ctrl or Shift.

I have also observed this problem when running kde3.5.2 on a powerbook. i tried remapping the default ALT+TAB to Command-TAB and no window list pops-up. In fact, using Command-TAB does not even walk through the windows, it only swaps between two windows.

i also checked xev and the Command key shows up as Super_L, as noted above.

The window pop up does work with CNTRL+TAB and OPTION+TAB (aka ATL+TAB on non mac keyboards) as well as SHIFT+TAB. 

I can "ditto" Dima's problem with KDE 3.5.2.
Also assigning "Win-Tab" to "Walk Thru Windows" doesn't work as expected either (it just does alternate between two windows).  "Win-Shift-Tab" does weird things too (doesn't always switch when you release the keys).

This bug still exists in kde 3.5.6

Ok, since every comment seems to say something slightly different, let's make some things clear:
- which shortcuts do work and which ones don't work for 'walk through windows'?
- the ones that don't, do they work for unrelated shortcuts (say, maximizing a window)?
- what's your xmodmap output?

Shortcut win+'any key' in System->Navigation->any of the walk through. 

Examples (r could be any other key):
If I assign win+r to 'walk through windows' it only cycles through the active window and the previous one (no window list pop-up is shown). 
If I assign win+r to 'walk through desktops' it cycles through the active and the one active before (e.g. when I was on desktop two and switched to four it cycles 2->4->2->4...).

When I assign win+'any key' to a shortcut outside of this group it works like expected but most of these shortcuts toggle something (e.g. maximize / minimize window). 

xmodmap
xmodmap:  up to 4 keys per modifier, (keycodes in parentheses):

shift       Shift_L (0x32),  Shift_R (0x3e)
lock
control     Control_L (0x42),  Control_R (0x6d)
mod1        Alt_L (0x40),  Alt_L (0x7d)
mod2        Num_Lock (0x4d)
mod3        Menu (0x75)
mod4        Super_L (0x25),  Super_L (0x73),  Super_L (0x7f),  Super_R (0x74)
mod5        Mode_switch (0x5d),  Mode_switch (0x71)

.

*** This bug has been marked as a duplicate of 140023 ***