it has happened to me many times, after instalation of forge my minecraft crash and i have to recover a backup in order to play. Here is the error log
Generated 13/08/13 04:46 PM
-- System Details --
Details:
Minecraft Version: 1.5.2
Operating System: Windows Vista (x86) version 6.0
Java Version: 1.7.0_25, Oracle Corporation
Java VM Version: Java HotSpot Client VM (mixed mode), Oracle Corporation
Memory: 452048584 bytes (431 MB) / 518979584 bytes (494 MB) up to 1037959168 bytes (989 MB)
JVM Flags: 2 total; -Xms512m -Xmx1024m
AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
Suspicious classes: FML and Forge are installed
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
FML:
LWJGL: 2.4.2
OpenGL: GeForce 9500 GT/PCIe/SSE2 GL version 3.3.0, NVIDIA Corporation
Is Modded: Definitely; Client brand changed to 'fml,forge'
Type: Client (map_client.txt)
Texture Pack: Default
Profiler Position: N/A (disabled)
Vec3 Pool Size: ~~ERROR~~ NullPointerException: null
java.lang.NullPointerException
at net.minecraft.client.gui.FontRenderer.getFontTexturePack(FontRenderer.java:1144)
at net.minecraft.client.gui.FontRenderer.func_98306_d(FontRenderer.java:222)
at net.minecraft.client.gui.FontRenderer.func_98304_a(FontRenderer.java:150)
at net.minecraft.client.gui.FontRenderer.<init>(FontRenderer.java:112)
at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:407)
at net.minecraft.client.MinecraftAppletImpl.func_71384_a(SourceFile:56)
at net.minecraft.client.Minecraft.run(Minecraft.java:732)
at java.lang.Thread.run(Unknown Source)
--- END ERROR REPORT 79f933cc ----------
Thank you