Have been having the same problem the last few days. I run LW, all is well for half an hour or so and I use other programs or surf. Then when I go back to LW all I get is a blank screen. Task manager says its still running but in the processes function it shows it as using none of the processor.
Has been running ok for the last few hours but has been a frustrating couple of days. Am running 4.12.3 pro.
Did the same as shuvro last night and same result, LW froze.
Never had too many problems before, am wondering if its anything to do with the latest version as I only installed it a few days ago.