Multiple Modpacks Crashing on Startup

[Scout11221]

Title:

Multiple Modpacks Crashing on Startup​

Launcher Version:

1.4.12​

Modpack:

Simply Astronomy​

Modpack Version:

1.5.0​

Log Link:

http://pastebin.com/AifuYAQ6​

Details of the issue:

This happens with multiple FTB modpacks, and even with AT Launcher packs. Sometimes I'm able to play with no problems for hours on end; no lag, stable fps, etc. Then, today, the game crashes when I try to enter my world. Sometimes I can walk around for a few seconds but it crashes when I open my inventory, and other times I don't even get past the main menu. Sometimes if I don't touch it for a few weeks I'm able to play it again, which is what happened yesterday. I have updated everything, Java, the modpack, the launcher, etc. I have 64-bit windows, a quad core processor, 8 gigs of RAM and more than enough graphics capabilities. All of my video settings in minecraft are set to low and I can't for the life of me translate the error logs and figure out what's wrong. I'm at my wits end and any help would be appreciated.​

 

[Booker The Geek]

Do me a favor and install the vanilla launcher, start a game from it.

Then post the next crash you get here from the FTB launcher.