If you’ve updated to a recent version of Firefox and also use the Flash Debug Player to debug Flash & Flex apps, you may already be painfully aware of the recent changes to the way Firefox 3.6.6 handles its plugins.
Now, rather than simply alerting you, letting you dismiss the error and continue on your merry way, Firefox takes control and kills the process for you because it detects that something is wrong. This completely disables the plugin and prevents you from debugging your app (while making you hang around for 45 seconds, just to infuriate you that little bit more) ;]
This also causes a problem during general day-to-day surfing because any site that doesn’t handle errors properly and/or throws null objects ( … yeah channel4.com I’m looking at you!) will also result in your Flash plugin being disabled.
You need to go in to the Firefox config settings (type about:config in to the location bar) and search for dom.ipc.plugins.enabled.npswf32.dll – double click that to set it to false. You may also need to set dom.ipc.plugins.timeoutSecs to -1. Now restart your browser and you should once again be able to debug your apps and dismiss the warnings as you used to do in the good old days. Ahhhhh bliss.
More info here.
In Firefox 4.0.1 dom.ipc.plugins.enabled.npswf32.dll (needed for the solution above) no longer seems available. You can still try disabling the plugin-crash-detection as follows: dom.ipc.plugins.timeoutSecs to -1