White and grey flashing specks on screen

My Xbox keeps getting flashing specks on the screen. During startup they appear but stop in the Xbox Dashboard. When I play a game the specks appear again and it interferes with my gameplay. Sometimes the startup is completely flawless but when it reaches the Dashboard vertical grey bars appear from the bottom  The bars range in size. This has been happening since January I think. Early on it would clear up after about 20 minutes gameplay. For the past three months it doesn't clear up. I have two TV's and I have tried plugging in my Xbox 360 on both. I even tried using HDMI and AV cables but the specks still wouldn't clear up. The HDMI specks appear smaller (I'm assuming due to more pixels). I have tried removing all cables, disc and hard drive and left it for a day. It still didn't work. Has anyone had this problem before and how can I fix it? When I tried to get a repair ordered, it would give me error 1134. BTW I have a Xbox 360 Slim 250 GB.