How much RAM do you have?

How much RAM does you system use up when this game is NOT running?

What browser are you using? What version of flash?

Generally speaking, flash crash is either due to unstable browser/flash installation/version OR due to memory overflow. This game, or the flash player thereof, could use up 1GB of RAM easily, so you need that much headroom.

If you have sufficient RAM, try uninstalling and reinstall your browser (and flash thereof, should it need one). afaik chrome and firefox are popular and stable.