I was about to create a ticket. This isuses is driving me insane. I'm on Windows 7 x64. Using Dual Monitor. I was having the exact same issue on Windows 8 x64 with different hardware. I'm pretty sure everyone with dual monitor have this issue.

If you press "tab" to check your inventory the mouse cursor will often ends up on your other monitor. This is getting really annoying and almost game breaking IMO because if I click the mouse button it will lose focus and alt-tab the game. It always take me a while to find my cursor after pressing ESC or using the Inventory. Please, make this a priority.