Hello all. I have brought the 21,5" iMac 1 week ago. I just chosed the preconfigured model. But i have had some problems with it. When the computer has been to sleep for some hours, it wont wake up with click on keyboard or on the mouse. I will have to use the powerbutton, where the computer then comes with a error, but it starts up. What shall i do? It have had the issues from the day i got it. Thanks.