It's my understanding that the Adobe Flash Player has two ActionScript Virtual machines. AVM1 and AVM2. It is supposed to detect whether a swf contains ActionScript 1/2 or ActionScript 3 and automatically select the proper virtual machine. The latest releases of the Flash Player 10.0.40+.x are breaking our oldest content. We speculate that it is not detecting the version properly because flashlog.txt reveals lots warnings about "undeclared" variables. Our oldest code uses ActionScript 1 and 2 and thus all variables are of course undeclared by AVM2 standards. So, we're wondering if we can do something, short of recompiling 10 years worth of products to make the latest Flash Player run our products. One idea is to pass in a version number through FlashVars, and I'm hoping someone out there might know for sure if this is worth persuing.