Application deleted itself after crashing

The game deleted itself after it crashed late morning on the 3rd June 2012

What I expected to happen was...:
i expected the game to reload (as it normally does) after it had crashed

What actually happened was...:
After it had crashed i went to re-open the application and it wasn't there

Steps to Reproduce:
1. put down multiple signs
2. the game will lag
3. after multiple signs are placed it will eventually crash
(However like i have already stated it normally crashes after i put down signs but then i can go back onto the app)

This has put me off purchasing Minecraft on PC due to nearly a years worth of solo and multiplayer building being deleted, the price seems to high after what i have experienced