I have a laptop with Ubuntu 14.04, when I lock my computer and try to unlock it after some time has passed (not if I do it immediately) the first time I try to unlock it, it will tell me that my password is wrong. When I enter my password a second time it unlocks as it should.
The first few times I though that I just typed my password wrong, but since then I've tried to type it very slowly and carefully. So I am 100% sure that the password I enter is correct.
I've also checked if the first key isn't recognized, but even pressing space a few times and deleting every character after that has the same result.
Any idea why?