Open Game either crashes or hangs when I try to open my world

[Slowking]

Summary of the problem Game either crashes or hangs when I try to open my world

Pack Version 1.5.1

What is the bug? The game crashes or hangs when I try to open my single player world. It happened for the first time after updating from 1.4.0 to 1.5.1 and happens every time now.

Mod & Version

Link to log file http://paste.feed-the-beast.com/view/4626c670

Is it repeatable? yes

Known Fix

 

[Slowking]

Any ideas on what might be wrong here? I'd like to be able to update to newer versions of the pack. Would be sad if my world was forever stuck at 1.4.0

Edit: I overlooked this crash report before: http://paste.feed-the-beast.com/view/a485e681

 

[Slowking]

Does really nobody know what's wrong?

 

[Ashzification]

What's wrong:
Your Java is out of date
You aren't allocating enough RAM
A block at this locaiton is angry- Block location: World: (357,46,7)

Often, when updating pack versions, world saves become incompatible because of changes in the configs.