I am also having this issue (approx daily). I'm running Ubuntu 14.04.2, with multiple monitors and an nvidia graphics card.
I'm afraid that I can't provide any logs/traces right now, but I can corroborate the thing about having to unlock twice. I can perhaps provide some more vague-but-useful information, though! I have a custom lockscreen background (unfortunately, I can't remember what method I used to set that). When this bug happens, the lock screen changes to the default Ubuntu background - the same as when I initially login after starting the PC. Once I've logged into this lockscreen, the screen goes black for a fraction of a second then it returns with the usual lockscreen with the custom background image. Once I've logged into that lockscreen, I am back at my desktop but with all apps closed.
I am also having this issue (approx daily). I'm running Ubuntu 14.04.2, with multiple monitors and an nvidia graphics card.
I'm afraid that I can't provide any logs/traces right now, but I can corroborate the thing about having to unlock twice. I can perhaps provide some more vague-but-useful information, though! I have a custom lockscreen background (unfortunately, I can't remember what method I used to set that). When this bug happens, the lock screen changes to the default Ubuntu background - the same as when I initially login after starting the PC. Once I've logged into this lockscreen, the screen goes black for a fraction of a second then it returns with the usual lockscreen with the custom background image. Once I've logged into that lockscreen, I am back at my desktop but with all apps closed.