I am just getting started with Flex & hitting a lot of roadblocks. Getting files for Day 1 helped. When I try to "run" a project I get asked for Flash Player 9. I uninstalled Player 10, found Player 9 for developers, installed, but Flex still does not see it. If I tell Flex to use current player I get bounced to a command prompt.
So, what Flash player are you guys using & ...how?
Probably the same one you're using at http://www.adobe.com/support/flashplayer/downloads.html.
Adobe Flash Player 9 — Debugger Versions (aka debug players or content debuggers) for Flex and Flash Developers
On occasion though I have to completely uninstall Flash player first and then install the plug-in and activeX components.