This issue has been reported several times. See bug 437241, bug 440769, bug 441482, bug 441510 and bug 441502.
I personally run into this issue randomly (not so often) on Mac OS X from time to time. Closing the current window solves the issue.
This issue has been reported several times. See bug 437241, bug 440769, bug
441482, bug 441510 and bug 441502.
I personally run into this issue randomly (not so often) on Mac OS X from time
to time. Closing the current window solves the issue.