Mouse Problems in Some Games: GTX 560 TI i5 2500k

I just built a new system running Windows 7 x64 and am having some weird problems with a few games.

When I boot some games (through Steam and actual disc) the mouse appears to point normally but wont click in most cases. I've noticed that if I move the pointer to random spots on the screen some menu items will highlight as though I've got the pointer over them and I can click on them. (Ex - mouse sometimes highlights and clicks offset about 3 inches to the right - which makes menu options on the far right not work.)

I'm using an EVGA GTX 560 TI DS SuperClocked with an Intel i5 2500k on a Gigabyte Z68MA-D2H-B3 motherboard with 8GB 1600Mhz ram. I've re-installed the graphics driver (which was the newest one anyway) and installed everything that came on the Gigabyte disc (including all the crapware). I've also downloaded and updated the Gigabyte drivers.

I'm stuck and don't know what to do. I've had a few games start working after uninstalling them and re-downloading them about 3 times, so I'm not really sure what's going on.

I've also tried different mouses - bluetooth, wireless, wired, and P2.

Which piece would cause this? The Mobo, CPU, GPU, or Windows? I've gotta know just in case it's a hardware issue because I'm still in the return window