So, I don't exactly know when this might have started happening, as I haven't played skyrim in about a month. But after downloading and installing dawnguard today I loaded up my game and quickly learned that I cannot attack. Which is to say that I tap mouse 1 or mouse 2, and nothing happens. I can still power attack, I can swap out my gear, I can draw or sheath weapons or spells. In fact I can draw weapons or spells by tapping mouse 1. But I can't perform any normal attacks. I searched around and saw that some people had similar problems (from months or years ago) and tried things such as deleting my preferences file, deleting the skyrim.ini in my games folder, and either changing the keys and/or resetting them to defaults. Whatever keys the attacks are mapped to react the same way as they did as on my mouse, I can draw weapons and spells, select things in my inventory, and power attack, but cannot otherwise attack or cast spells. So of course, I turn to you, and hope that you can provide help of any kind.