Complete Computer Freeze

When I play Minecraft for a while (after about a minute or so in a jungle biome) my entire computer crashes, specifically the following happen: the screen turns a solid colour (usually light pink or blue) while the Minecraft music and sound effects continue to play, I am completely unable to interact with the computer (e.g. ctrl+alt+delete does not work).

After the crash I have forcefully restarted my computer (using the power button), also there is no crash report in my .minecraft folder. I have attached my latest log, but the crash probably occurred at least 20 seconds after the last entry.

I have just purchased and installed Minecraft, so it has not been modded, and have tried playing with various graphic levels (specifically increasing\decreasing the render-distance) but the effect appears to be the same. I also doubt it is a hardware problem as I can play more graphic intensive games (such as with lower frame rates) without any crashes.

(p.s. the Jungle biome I mentioned is a "Large Biomes" world with seed -8426229644075309914)