I always encounter this, but cannot pin point the pattern/cause. It is very annoying. But seems we are talking 2 issue here.
1. Not able to drag/drop items from bag to ground. Seems it will work again after reload/restart.
2. Drag to hot bar. If you drag skill/spell to an item in the hotbar, it may place it there, but the item still exist, and when you click or use hotkey, the item beneath is used, instead of the skill/spell showing "on top".
