Double Blocks & dissapearing fishing hooks

When I place blocks it double places the block. this gets really annoying sometimes and causes me to have to stop building and break the block. So then I have to constantly stop and break a double every time I place one block, I have checked my mouse and it is perfectly fine, and I have restarted minecraft a lot, but the problem does not go away. Also it makes it hard to move things around in my inventory, it won't let me click and place it in a square, it stays linked to my cursor instead. Another problem I found out is that if you throw a fishing hook it sometimes resets the fishing pole back to the icon of it with a hook attached to it. Can you please fix these issues in 1.8 or before? It gets hard to build. Thanks!