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

Install optifine AFTER Forge.