Is this happening only on one computer? I.e. if you publish your Catalyst project and put it online, then visit the website from a different computer, does it load correctly there?
If it's happening on all computers, make sure you've uploaded everything in the deploy-to-web folder -- if you are missing any of the .swf or .swz files, that may explain this error.
Also, have you ever installed a prerelease version of Flash Catalyst, Flash Builder 4, or the Flex SDK? Or a prerelease version of Flash Player?
Lastly: what operating system are you running?
O man thanks for your reply, i didn't really expect reply from anyone. actually i didn't even put it online yet. i tried to "run" it but that's the message show up on the explore. and ya i am still using the beta one. is there anything i need to install before making it work?
I'm getting the same error on my site that I made with the Flash Catalyst Beta. Is there a way to solve? I am unable to even open my project file now that the beta is over.
Please see this recent post: http://forums.adobe.com/message/3277736#3277736
Your best option is to open your project in the shipping version of Flash Catalyst CS5 and re-publish it. Catalyst CS5 can open projects that were created with the beta 2 release (October 2009) or newer.
If your project won't open, then it was probably created in an earlier beta/alpha version of Catalyst. If you know how to write Flex code, with some work you can upgrade these old projects by hand: import the project into Flash Builder 4 and then resolve any problems you encounter with compiling and running the project.
Sorry for the trouble -- hope this info helps,
One would never expect that after spending so much time working and learning to use a piece of Beta software that after all that hard work it is VOID unless they purchase the software. It doesn't seem fair.