I got a temporary solution that will almost erase that annoying dot... just go to personnalize , window color, choose the preset color the one to the right on the 2nd row, which should be called ''icy or freeze'' in french its 'givre' , anyway pick that color, and activate the transparency , and your white dot will almost be almost invisible....
Hope this helps until they patch that problem out....
By the way, this had never hapened to me before tonight and it started after i installed my new nvidia drivers to the 280.26 version.. I should have kept my old drivers, but I was having an issue with a 'the display driver was not responding and was restarted' message....
since ati users have the same problems, i guess the its linked to something included in both nvidia and ati latest drivers...