This problem started once 1.3.1 was released and has continued ever since. The problem is the nearly constant crashing and the "javaw" process that does not stop once Minecraft closes. You also cannot kill this process through task manager for some reason. The only way to kill it is to restart your computer.

Also, everytime I close Minecraft (or it crashes) and open a new Minecraft window another "javaw" process will start and run simultaneously with the last "javaw" until I restart my computer. Multiple javaw processes will build up until they crash my computer from eating up all the RAM.

The games crashed randomly while I am playing multiplayer. I haven't noticed any consistencies when it has been crashing. Sometimes crashes while I'm in-game, other time while I'm just in the Minecraft client menu. It seems to be crashing randomly.

I'll tell you what doesn't work to fix it.

1. Clean Minecraft update still causes the problem.
2. Using a different launcher still causes the problem.
3. Using batch files still causes the problem.
4. Whether it Crashes, You click the x button, you press terminate the process, or you click the Quit Game button, it still causes the problem.
5. Clicking End Process Tree or End Process still causes the problem.
6. Using mods or not still cuases the problem.
7. Having Java 7 Update 5 or Java 6 or Java 7 Update 3. It doesn't matter. It still causes it.

Here's a link to a thread on Minecraft Forums:

http://www.minecraftforum.net/topic/1405977-minecrafts-java-process-will-not-die-on-closure-or-at-all-for-that-matter/