Responda aos cuidados de Allen Matsumoto
If you're running Lion, one of the MBP models listed below, AND have a third-party video driver of any kind installed, the "can't drag and drop" problem can occur.
MacBookPro5,1 (15-inch, Late 2008) MacBookPro5,2 (17-inch, Early or Mid 2009) MacBookPro5,3 (15-inch, Mid 2009)
My 3d party driver happens to be from the AirDisplay app, though iDisplay and various USB display attachment products also install 3d party video drivers and have the problem. (http://blog.avatron.com/post/20422624624/air-display-on-lion-with-nvidia-9400-9600)
The only workaround until Apple fixes the issue (which is seeming less and less likely given how long it's been around) is to be sure to put your MBP to sleep after any restart.
I restart so infrequently that this always crops up and I have to look it up to recall the problem and fix. Hey, maybe I'll find my own post next time, Memento-style!