We had a report the the "Drag and Go" feature of a program called Winsplit Revolution could cause that problem. (here).
That's the only possible cause I am aware of, but similar tools that modify the desktop's behavior are worth considering as well.
We had a report the the "Drag and Go" feature of a program called Winsplit Revolution could cause that problem. (here).
That's the only possible cause I am aware of, but similar tools that modify the desktop's behavior are worth considering as well.