Please see
For some reason when I go to the bottom, hovering is not working
Source can be viewed using "View source"
Please tell me what to do

Also, I wanted to ask how to debug in such cases as when I wrote document.write("something here"), the moment it got executed I got There is an error in line so and so..do you wish to debug? etc....
How can I debug javascript code?

Anyone please???

It works. But your changing of coordinates of tooltip box is strange, that's why you can't see the box, sometimes. Why don't you use mouse coordinates for moving box?