A week ago I noticed a weird Lion symptom, and posted a vague description of one this problem.
Today, after some tests, I came to a conclusion that this bug reproduces whenever a the computer is logged into while plugged to a certain display, and then being plugged to a different display.
The only thing I can think of is that the display data is saved, and a conflict occurs upon the plugging of a different display.
Any idea as to how I can delete or reset this data?