Hi I've only just signed up as recently purchased my first mac (rMBP). After having updated to Mountain Lion, I'm getting a blank black screen after logging in (type in password, press enter -> black). A hard reset and booting up again seems to fix it (it allows me to log in). This is probably happening about 50% of the time I try to log in. Turning off Automatic Graphics Switching seems to resolve it but means it uses the NVIDIA card 100% of the time. Any advice? Is it worth getting it replaced or could it be a simple driver issue with the Intel graphics? Anyone else experiencing this at all? I'm new to Macs so I'm not sure if it's a common or easily-resolvable issue. Thanks.