When I boot my R-Pi connected with the TV (using RC4 cable), it booted by default to the console mode without problems. But, when I booted the device connected with my monitor (using HDMI to DVI cable), it booted by default to a GUI login, which is not logging in even with the correct credentials (username: pi, password: raspberry). It returns to the same GUI login, after a black screen. What could be the problem? Somebody help.