Drag and Drop problem, Files won't drop in OS X

I have a MacBook Pro 15" i7, Snow Leopard 10.6.8.

Files won't "drop" after dragging them.

I've restarted my computer several times, and repaired disk permissions as well as verified the disk – and the results told me my MacBook Pro was fine.

What should I do? What's causing this?

Solution 1:

An anonymous user posted the following as a suggested edit to one of the answers to this question:

This seems to be related to Avatron's Air Display, see this post.

From the linked web page:

Here’s the current status: IF you’re running Lion AND if you have an NVIDIA 9400M/9600M chipset AND you have a third-party video driver installed, THEN you will not be able to release the mouse button while drag-dropping something.

Well, it turns out that the drag-drop bug only manifests itself if you haven’t done a Wake From Sleep since your last Log In or Restart. So there’s a workaround: After each Log In or Restart, close your MacBook Pro, wait for it to sleep, and then open it again to wake it. It’s a little bit of a pain, but it’s there as a workaround if you want to use Air Display on one of these Macs.

Solution 2:

That happens to me in Lion after I boot my computer.

My solution: put it to sleep and wake it and everything will be ok

Solution 3:

Open System Preferences » Trackpad and make sure you don't have Drag Lock set there.