Desktop suddenly darkens and menu bar and desktop icons disappear

Hi guys,
Some times (not very often) suddenly the desktop darkens, and the menu bar and the disktop icons disappear, while the dock remains. I have to click in order to return!
What causes this thing?

P.S. Before awhile, that this happened again, I looked at the console and saw these two events:

1)**** [IOBluetoothHostControllerUSBTransport][SuspendDevice] -- Suspend -- suspendDeviceCallResult = 0x0000 (kIOReturnSuccess) -- 0x3000 ****

2)setPresentationOptions called with NSApplicationPresentationFullScreen when there is no visible fullscreen window; this call will be ignored.

But I cannot specify the exact time it happened, in order to see if any of those two messages are related.

I could be wrong (error messages in applications really need to be less cryptic) but it looks as if something is trying to go full screen and partially succeeding. Do you have something open that is designed to display something in full screen?

vansmith said:

I could be wrong (error messages in applications really need to be less cryptic) but it looks as if something is trying to go full screen and partially succeeding. Do you have something open that is designed to display something in full screen?

Click to expand...

This has occurred in different conditions, even without any activity (as a matter of fact, now that I am recalling the issue, it has happened when no applications are running).