Minecraft - Corrupted Savegame?

As some of you might have noticed, I'm an avid minecrafter and been busy for months with creating my ow little world. But, once again, fate decided to shovel sh*t in my face!
Whenever I try to load up my save, the game freezes and gives me this notification:

Minecraft has crashed!
----------------------

Minecraft has stopped running because it encountered a problem.

If you wish to report this, please copy this entire text and email it to support@mojang.com.
Please include a description of what you did when the error occured.



--- BEGIN ERROR REPORT a1dce528 --------
Generated 17.04.11 21:22

Minecraft: Minecraft Alpha v1.2.3_01
OS: Windows Vista (x86) version 6.0
Java: 1.6.0_24, Sun Microsystems Inc.
VM: Java HotSpot(TM) Client VM (mixed mode), Sun Microsystems Inc.
LWJGL: 2.4.2
OpenGL: ATI Radeon HD 2600 XT version 2.0.6747 Release, ATI Technologies Inc.

java.lang.NullPointerException
at bv.a(SourceFile:157)
at f.a(SourceFile:978)
at ka.c(SourceFile:372)
at ka.b(SourceFile:312)
at net.minecraft.client.Minecraft.run(SourceFile:626)
at java.lang.Thread.run(Unknown Source)
--- END ERROR REPORT 82f38764 ----------

Googled it, tried a lot of stuff, reinstalled, but the savegame still is corrupted.
Long story short, it doesn't work, and it really bugs me because I literally spent hundreds of hours with this game.
This is my last resort, if any of you guys could actually come up with a solution it would be more than awesome!


Also, check out MorphThing.com
its perfect if you want to waste some time.