I try running the minecraft mod program and it says minecraft .exe has stopped working then I get a Microsoft .Net Framework Error.
Make sure u have the latest "Microsoft .Net Framework" install on yr computer and u should b good to go.
as shadow has advised update your .net framework to 4.0, although i personally dont think this will have any effect on your save. minecraft.exe crashes when the save is unopenable.. meaning it is corrupted and not capable of being fixed.