"GUI mode" is a misnomer. It's saying that it could not start the X client because the graphics hardware could not be properly configured and that the configuration failed because the X auto-configuration system could not reliably determine the make and model of one or more of your bits of graphics hardware.
If the system was working, you may have developed a hardware problem. Although in the case of laptops, where the hardware tends to be pretty unusual to begin with, it's also possible that the hardware you are running isn't well-supported by the available drivers. The drivers might be just good enough to make it work sometimes and not other times. One possible way around this is to completely power off the laptop before booting, thus allowing the hardware to all clear to its base state.
You should check to see what graphics hardware you have and whether there are possible driver updates. If you're into blood and guts and transistors in your teeth, you can also hand-craft an xorg.conf file yourself, but that's not a task for the faint of heart if for no other reason than half the online documentation you run into will be out of date and send you down false paths.
The secret of how to be miserable is to constantly expect things are going to happen the way that they are "supposed" to happen.
You can have faith, which carries the understanding that you may be disappointed. Then there's being a willfully-blind idiot, which virtually guarantees it.