Alright, I bought the new 360 slim a year ago, and it's been working fine, however, some things have started to come up recently.
First: The console has begun to take around 30 seconds to start up from the original 4-5. When I first turn it on, it will recognize my wired controller on the light portion of the startup button, but then it waits for around 30 seconds on full black screen before the 360 logo pops up with the starting animation. I have tried clearing my system cache, and removing my HDD, but to no avail.
Second: Twice in the past two days I have had to shut off my xbox and restart it due to the screen fragmenting slightly into green, purple, and other colored pieces. The console eventually turns to blackscreen, and a single red light appears on the top right corner of my 360 (top right corner if it is standing up straight, and not on its side). I then restart it. The second time I have had to do this, the console didn't even start up, it simply showed the single red light. I moved the video cables around and checked their connections to the proper ports, and the console started up fine after that.
I game with VGA cables on a 23 inch computer monitor, and I have had the cables for a few years now. I have a suspicion that they may be failing due to their age, but I am not sure.