Startup/Shutdown freeze on fairly new computer

Hi, I recently built a new desktop and for the most part, I'm very pleased with the results. However, every now and then I get a very strange error. Three times in the past two weeks the computer has frozen right after the "Starting Windows..." screen. The screen is black with the occasional flicker. The first time it happened, I let it sit for 10-15 minutes to see if it would resolve itself, but it stayed that way. A hard reset and it was working fine, I didn't take any action to correct it for i figured it was just a goof. However, since then it has happened twice. I didn't want to think anything of it, but last night another symptom occurred. I clicked shut down and then walked away from my computer for about 10 minutes. When I came back, I was surprised to see the monitor was still on. Usually it shuts down in 20 seconds or so, if it isn't installing updates. When I approached the screen, I saw that it said "Shutting down..." like it would normally, however, the screen was blurry, (the text was hardly legible) and on the left hand side, the picture was pixelated (it appeared to be checker boarded blue and white, the blue being the standard color of the shut down screen).

Here are my specs.

OS: Windows 7

Mobo: ASRock FM2A75M-DGS FM2 AMD A75 (Hudson D3) SATA 6Gb/s USB 3.0 Micro ATX AMD Motherboard

APU: AMD A10-5800K Trinity 3.8GHz (4.2GHz Turbo) Socket FM2 100W Quad-Core Desktop APU (CPU + GPU) with DirectX 11 Graphic AMD Radeon HD 7660D

RAM: CORSAIR Vengeance 16GB (2 x 8GB) 240-Pin DDR3

HDD: Seagate Barracuda 1TB

PSU: Coolmax 350w (temporary, I'm not overclocking or anything so I'm not too worried about replacing this right away)

My monitor, if it matters, is an old Quantex 10" (or so) connected via a VGA cable