Apologies if this issue has been addressed in other threads, but I wasn't able to find another problem description that matched what I've seen recently.
The following issue has occurred three times in the last week when the phone was in a locked state with the screen timed-out. Pressing the lock/power button did not turn the screen on. Long-press of the lock/power button did not turn the phone on or off. Only removing the battery and reinserting it allowed the phone to be turned on again. Once it came back on, the battery was still in good condition, so battery drain was not the culprit.
Has anyone else experienced this problem? I'm wondering if this is a hardware or software issue. I'd really rather not hard-reset the phone, so before I go down that path, I wanted to get input from the experts.