Cannot change window focus in 7

This morning I became unable to switch the focus of my window. When I am in Mozilla, I can use the mouse as normal but I cannot use my taskbar, start button or another program (with the mouse) even if I alt-tab into it. If I close mozilla, then sometimes I can access my desktop with the mouse but not the taskbar. The windows button still works properly and when I alt-tab into another program, I can use the keyboard to navigate, but not the mouse. Any suggestions?

Thanks,

Toshiba Laptop
3 GB Ram
2-core 1.6 Ghz
Windows 7, latest updates