These 3 pictures show my mouse in slightly different locations on the "search forums" searchbox. Unfortunately, fraps doesn't capture the mouse location, so I had to superimpose fake mouse images into the picture in the most precise location I could, so these are accurate, albeit fabricated.
The first picture shows what happens when I go to activate the search box underneath my "teahousemoon [ 0 ]" personalized link box for the site. If I went down just a tiny bit more (approx. the bottom third of the search box itself) with my cursor, I would be able to activate the search box.
The second picture shows what happens when I am able to activate the search box (with the I cursor appearing). This can only be activated on the bottom third of the search box.
The third picture shows what happens when I move my cursor approx. 1 frame above the location my cursor is in for the 2nd picture. With this standard mouse pointer, I cannot activate the search box, and clicking has no response.
I should also note that my resolution is 1080x1920.
I hope this helps, thanks Tom!