I was going to start my own thread about this, so I'm glad to have found this one.
I've had this problem for years through multiple installs. Whether it started with 8.0 I'm not sure (I'm leaning towards it being in Win7 too, but it's been a long time), but the latest 8.1 doesn't resolve it.
Until now, my working theory had been that it was some sort of graphics-related resource depletion due to the fact that I don't have a dedicated graphics card (I use what's built-in to the Core i5-2500K). Unfortunately, your profile shows that you have dedicated graphics.
So...I'm at a loss. It is annoying, and it only seems to happen after a good part of a day of active use. Sometimes I can go a day without seeing it at all, in fact. Is that about the same for you?
The only thing that I can think of now is some program that we both use a lot. If you want to compare installed software, let me know.
There is an easier way of temporarily resolving it short of a reboot, however. Make a batch file along these lines:
I left Snagit32 in there because it's an example of a program that normally sits on the tray (not to be confused with the taskbar) and doesn't come back after restarting Explorer.exe (even though Snagit32.exe is still in memory). So, I kill those programs as well and restart them in the batch. If you don't have any programs that show this problem, then you needn't bother with adding them to the batch.
taskkill /F /IM explorer.exe
taskkill /F /IM snagit32.exe
start /d "C:\Program Files (x86)\Snagit" Snagit32.exe