Hello,
After launching MINECRAFT, it's impossible to open existing worlds. Error message below and log file attached.
We previously have been playing minecraft without problem for several months.
We tried to use previous versions of minecraft (9.1 or 9) but the problem is still the same.
Thand you for your help.

Completely ignored arguments: [--nativeLauncherVersion, 301]
[14:07:22] [Client thread/INFO]: Setting user: Bat56
[14:07:24] [Client thread/INFO]: LWJGL Version: 2.9.4
[14:07:24] [Client thread/INFO]: Reloading ResourceManager: Default
[14:07:25] [Sound Library Loader/INFO]: Starting up SoundSystem...
[14:07:25] [Thread-5/INFO]: Initializing LWJGL OpenAL
[14:07:25] [Thread-5/INFO]: (The LWJGL binding of OpenAL. For more information, see http://www.lwjgl.org)
[14:07:26] [Thread-5/INFO]: OpenAL initialized.
[14:07:26] [Sound Library Loader/INFO]: Sound engine started
[14:07:27] [Client thread/INFO]: Created: 1024x512 textures-atlas
[14:07:39] [Server thread/INFO]: Starting integrated minecraft server version 1.9.2
[14:07:39] [Server thread/INFO]: Generating keypair
[14:07:39] [Server thread/INFO]: Preparing start region for level 0
[14:07:40] [Server thread/INFO]: Preparing spawn area: 3%
[14:07:41] [Server thread/INFO]: Preparing spawn area: 84%
[14:07:42] [Server thread/INFO]: Changing view distance to 16, from 10
[14:07:42] [Server thread/INFO]: Bat56[local:E:a1a81f53] logged in with entity id 80 at (-326.94926095776214, 72.0, 379.89226063325054)
[14:07:42] [Server thread/INFO]: Bat56 a rejoint la partie
[14:07:45] [Server thread/WARN]: Keeping entity Chicken that already exists with UUID ae2493a8-3281-4aaa-8596-1961ea0987bb
[14:07:47] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 4630ms behind, skipping 92 tick(s)
#

1. A fatal error has been detected by the Java Runtime Environment:
   #
2. EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x00007ffdab5a9adc, pid=9524, tid=6376
   #
3. JRE version: Java(TM) SE Runtime Environment (8.0_25-b18) (build 1.8.0_25-b18)
4. Java VM: Java HotSpot(TM) 64-Bit Server VM (25.25-b02 mixed mode windows-amd64 compressed oops)
5. Problematic frame:
6. C [ig8icd64.dll+0x639adc]
   #
7. Failed to write core dump. Minidumps are not enabled by default on client versions of Windows
   #
8. An error report file with more information is saved as:
9. C:\Users\ORSONI\AppData\Roaming\.minecraft\hs_err_pid9524.log
   #
10. If you would like to submit a bug report, please visit:
11. http://bugreport.sun.com/bugreport/crash.jsp
12. The crash happened outside the Java Virtual Machine in native code.
13. See problematic frame for where to report the bug.
    #
    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