All visible hexes are highlighted instead of movable hexes

[wy29]

The problem:
Usually, when I click/mouse-over a unit to move, it shows the movement range of that unit by highlighting the reachable hexes and dulling out the rest.
However, I experienced a few cases when the entire visible hexes are highlighted instead.

The pain:
When this happened, one can no longer see where the unit can move to easily.
The only way is to mouse-over over each hex to see the number of turns it will take for a unit to reach that hex.

I have experienced this a few times with and without fog on, so I think game settings are irrelevant here.
This problem is very hard to replicate and I only experienced it 4 times after playing Wesnoth for half a year.(From versions 1.2 to 1.4 now)
The problem goes away when I saved and reloaded the game.
Thus I was never able to get any useful information out of the logs.

I'm wondering if anyone else has experienced similar problems.

Additional info:
The last time I encountered this problem, I was playing Wesnoth 1.4.5 on WinXP SP3.
The ctrl + v and b still shows the correct movement range for enemy units.
All other parts of the game works fine, just the highlighting of movable hexes are incorrectly.

[Jozrael]

I can't understand why it happens to me too, but it is EXTREMELY aggravating. The only fix I had was just saving and then reloading from the save, which fixed it fine. No key combination that I could think of or alt-tabbing could fix it.

[Soliton]

You can press 2-7 to hilight hexes the unit can reach in those number of turns. Sounds like one of these keys might get stuck for some reason.