Command+right/left stopped working On a couple occasions since I installed Lion, the keyboard shortcuts ⌘+→ and ⌘+← have stopped working to navigate to the beginning/end of a line inside text fields and such.  Any ideas what's going on?

Notes:


My computer doesn't beep when I hit these shortcuts.
Keyboard Viewer shows that when I hold down ⌘, pressing left/right doesn't do anything.
When I hold down both ⌘ and ⇧, the arrow keys work fine.
The left and right arrow keys still work by themselves.
⌘+↑ and ⌘+↓, and ⌥+arrows still work.
⌃+A and ⌃+E still work.
I don't have any particularly weird custom keyboard shortcuts set up.
If it matters, I use 4-finger swipes and ⌃+arrows for switching desktops, two- and three-finger swipes for navigation, and three-finger swipes for Mission Control &amp; App Exposé.
No need to restart, these steps helped me:


Swipe 4 fingers up to show Mission Control
Select a full-screen app in the list of desktops
Swipe 4 fingers up to show Mission Control again
Select a text editor app on the main Desktop