Sorry but there are a lot of missing details here.
For example, if you were using a laptop with trackpad mouse control I might suggest that the trackpad itself is the problem as it is often too sensitive for such intricate manoeuvres. Solution? Change to a USB mouse and disable he trackpad.
But as I said, without those details that is only an example.
Mark
I recently began having problems trying to drag and drop files to a different folder. Every time I click and hold on the file to move it, the file opens, which makes it impossible to move the file. If I fiddle with it and manage to click on a "magic" spot - usually a bottom corner, I can eventually get the file to not open and I can then move it. I have not changed any settings on my mouse.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic