Looking for some solutions for a similar problem.
I've been playing on Technicpack for about a week or so and all of a sudden my left click stopped working in game. Right click still works but I can't use any left click functions besides dragging items around.
I tried starting a new world and experienced the same problem. However, when trying in vanilla minecraft or in the Tekkit pack everything works fine.
Once again, this problem seemingly came out of nowhere in the middle of when I was playing today
