I'm running Mac OS Leopard and using a Targus Bluetooth Laser Mouse and just recently, on two different computers, the mouse buttons stop being able to control Spaces. They work fine for activating Exposé but Spaces will not respond to any mouse buttons. Keyboard and hotspot activations work fine.
For over a year it has been working fine. Just made a clean install of OS X and still have the problem. Restarting fixes it, but it invariably returns if I use the computer for a while. Seems to happen after activating Spaces.
Also, I'm not using the Targus software to configure this. I don't have that installed and am just using the Expose & Spaces system preference pane to do this.
Update
Just got a brand new 2010 15" MacBook Pro with Snow Leopard and it was working great until this morning and it suddenly stopped working. I've rebooted, which always fixed the problem under Leopard, but isn't doing it for Snow Leopard.

Spacebarto a mouse button, later I've realized that Spaces is probably a program or so. – Nyuszika7H Jan 22 '11 at 14:04