?? Swapped HDD, now Firefox ignores mouse clicks??

[LB_BlueVue]

I just installed a new Seagate 7k-320GB.
I cloned my old drive onto it with Acronis True Image.
Everything worked fine, except that Firefox now has a really strange problem. When I click on a link, or any other button in firefox, it works. But after that, it ignores all mouse clicks, right or left, regardless of whether it's a link, a button, a menu, or even the red X to close the window.
Even stranger: if I alt-tab, or click on the task bar button of another program to bring it to the foreground, and the switch back to Firefox, then it will allow me to click on links again. WTF???

Any ideas??