pre release crashed

Minecraft Crash Report ----
// Ooh. Shiny.

Time: 4/5/16 6:16 PM
Description: Updating screen events

java.lang.RuntimeException: Failed to check session lock, aborting
at aze.i(SourceFile:64)
at aze.<init>(SourceFile:50)
at azb.<init>(SourceFile:21)
at azc.a(SourceFile:83)
at bcc.a(SourceFile:2089)
at bhh.a(SourceFile:212)
at bey.a(SourceFile:341)
at bhh.a(SourceFile:352)
at bey.k(SourceFile:404)
at bey.p(SourceFile:381)
at bcc.t(SourceFile:1575)
at bcc.av(SourceFile:962)
at bcc.a(SourceFile:392)
at net.minecraft.client.main.Main.main(SourceFile:124)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

– Head –
Stacktrace:
at aze.i(SourceFile:64)
at aze.<init>(SourceFile:50)
at azb.<init>(SourceFile:21)
at azc.a(SourceFile:83)
at bcc.a(SourceFile:2089)
at bhh.a(SourceFile:212)
at bey.a(SourceFile:341)
at bhh.a(SourceFile:352)
at bey.k(SourceFile:404)
at bey.p(SourceFile:381)

– Affected screen –
Details:
Screen name: bff
Stacktrace:
at bcc.t(SourceFile:1575)
at bcc.av(SourceFile:962)
at bcc.a(SourceFile:392)
at net.minecraft.client.main.Main.main(SourceFile:124)

– System Details –
Details:
Minecraft Version: 1.RV-Pre1
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.8.0_65, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 192349808 bytes (183 MB) / 252968960 bytes (241 MB) up to 1060372480 bytes (1011 MB)
JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 1.RV-Pre1
LWJGL: 2.9.4
OpenGL: Intel(R) HD Graphics 4400 GL version 4.3.0 - Build 10.18.14.4206, Intel
GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

Using VBOs: No
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs:
Current Language: English (US)
Profiler Position: N/A (disabled)
CPU: 4x Intel(R) Core(TM) i3-4130T CPU @ 2.90GHz