MR_LOOL

I dont know why it does this, but just as I have been in a singleplayer world for about 20-30 secounds, I crash! !NOTE! I HAVE turned up the amount of RAM usage to 10 GB! Still crashes! And I dont even use all that RAM. There are NO indication what so ever, that im going to crash, I have heard someone else having this problem, but then it just kinda vanishes? Look, I use the RECOMMENDED version of the pack, and I just want to play. I hope you can help me :/ Thanks.