Guys,
Magento has this problem with it’s upload image and browse images in the Manage Product page. Error console is saying:

throw new Error(myErrorMessage[1]);

Source file: “/js/lib/flex.js ”
The problem is that the upload code is not compatible with Flash Player 10.
a workaround is to first uninstall the flash player 10, and then download and install flash player 9:
uninstall your flash plugin/activeX through:
http://download.macromedia.com/pub/flashplayer/current/uninstall_flash_player.exe
install the old Flash 9 through:
http://download.macromedia.com/pub/flashplayer/updaters/9/flash_player_update6_flash9.zip
I know this is a short term solution. But Flash player 10 does this on purpose to prevent a security exploit. I guess the magento community will …