Hi, I've just started modding and was following the CK tutorial-2nd one with the first room builder-when I got this problem.
My visible cursor and the actual part that gets clicked or selected are different. ie, the cursor and the "bit-that-gets-clicked" moves in different velocity and of different displacement, it's like clicking a place that is completely different from where my cursor is pointing at.
It only happens in the render screen. Although I'm not sure if this is the cause, but I use G800 gaming mouse from ASUS and have resized my render window-again not sure if this problem occurred before the changes.
I saw the "ignoring click button reversal from control panel at windows" bug from the unofficial bug page and I tried to Logitech software to see if it fixes it, but it did not work.

Please help me!

Ok, I changed the render window to its default size and managed to fix it. So, I shouldn't resize the render window size?

Try to stick to the same aspect ratio of the render window then, that might be the issue rather than size.

Thanks for the tip, but I'm afraid it didn't fix it.
First, even though I had resized the window in scale with the default, the cursor and the click point keeps separating.
Second, the difference in velocity of the both-I think the click point's velocity increase is relative to the increase in the size of the window- makes it painful to navigate.