15w41b crashes when i load a world

Everytime the world loads a bit it crashes what it says:# Failed to write core dump. Minidumps are not enabled by default on client versions of Windows
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1. An error report file with more information is saved as:

2. C:\Users\NITRO\AppData\Roaming\.minecraft\hs_err_pid568.log
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3. If you would like to submit a bug report, please visit:

4. http://bugreport.sun.com/bugreport/crash.jsp

5. The crash happened outside the Java Virtual Machine in native code.

6. See problematic frame for where to report the bug.
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   AL lib: (EE) alc_cleanup: 1 device not closed
   Java HotSpot(TM) 64-Bit Server VM warning: Using incremental CMS is deprecated and will likely be removed in a future release