It seems that you're using an outdated browser. Some things may not work as they should (or don't work at all).
We suggest you upgrade newer and better browser like: Chrome, Firefox, Internet Explorer or Opera

fixanoid: Ok, so my game runs for a little bit and then hangs for no obvious reasons and without errors. Anyone else?
"Hard" lockups without any error messages usually means faulty hardware. I would start with RAM. Do you have problems like that with other games/applications?