1, first , uninstall your flash player in your computer , download the uninstall software of player;
2, install plugin for windows , download
3, download the lastest sdk of flex , the lastest sdk is 3.0.3.2228 , your can see your sdk of install in your computer, that it can be within adobe Flex Builder 3/sdks/3.0.0/flex-sdk-description.xml, the content of that is :
<?xml version="1.0"?> <flex-sdk-description> <name>Flex 3</name> <version>3.0.0</version> <build>477</build> </flex-sdk-description> . it is meaning of your sdk is 3.0.0.477 , your must update the sdk ;
your can see it in the website : http://opensource.adobe.com/wiki/display/flexsdk/Download+Flex+3
4, your must select the lastest sdk in flex builder .
5,that is ok.