Put the summary of the bug you're having here
Crash is happening repeatedly at my single player world every after 5 mins. Other worlds like my test world doesnt crash.
Environment
OS: Windows 8.1 (ver 6.3, arch x86)
Java: 1.7.0_60 (by Oracle Corporation)
Launcher: Minecraft Launcher 1.4.4 (bootstrap 5)
Minecraft: 14w28a (updated Wed Jul 09 23:42:36 CST 2014)
Fixed in 14w28b.
14w28a is outdated!