Crash-report

During the last period I have got several crash-reports and "Out of memory" messages. I have the newest launcher (1.3.11), so I do not think the problem is there.
Also when I go to another page at my computer the game goes into a "blackmode", where everything is black besides the mousearrow. If I then click where it should have been "Back to game", the screen is still black, but I can still run around.
Is there a way to solve that issue?