Something that has been happening to me the last month or so is when I go to shoot someone and the first and maybe second click of the mouse will not fire. I've noticed it mostly with SMGs but that may be only coincidental. It happened again a couple of days ago and I figured there must be something wrong with my wireless mouse. So, I bought a wired one, which I received and played with tonight. I had the same thing happen.
As you can imagine, this is very annoying. Many times recently I have gotten the drop on a guy, clicked to no effect, and got shot. Sad!
I was ready to just chalk it up to something on my end, but talking to some squaddies about it they said they've experienced a similar thing. I got to thinking that maybe this is happening to a lot of us, but it didn't seem obviously like a bug, so we wrote it off as clumsy click of the mouse or something. But maybe it is a new thing, so I mention it now.
I did a search of the forums. It's possible this guy had the same problem:
I have not experienced the escape/diff weapon thing. I'll try it the next time I fail to fire, assuming I miraculously don't die in the process.