Java error: BTM won't launch

[bwoodhouse729]

This seems like a great game, wish I could play it.

I'm running Windows 7, 64 bit.
Launching from Steam, my screen goes to black and I have to ctrl-alt-delete to see a message that Java Platform SE Binary has stopped working.

Launching from the blocks that matter folder using BTM_DBG_embedded_jvm_win gives a terminal with the following error:

Exception in thread "main" java.lang.NoClassDefFoundError: Files
Caused by: java.lang.ClassNotFoundException: Files
etc.
Could not find the main class: Files. Program will exit.

Any suggestions?