It sounds like you've hit a bug in Catalyst. If you send me your project, I can check it out (and maybe fix it). My email is my name (no spaces) at adobe.com.
Do you remember the steps you took to get here? Can you cause the problem to happen again in a fresh project? I'd love to get this bug fixed.
I'm also having the same problem too. As soon as I start adding interactions and playing with the transitions for my multi-link/page navigation. I get the missing "main.css" error. Once I get the error, it interferes with all my previous version of the page, making them also non-functioning.
Here is the code from the workplace where the error was identified:
Here is the error:
Description Resource Path Location Type
Problem finding external stylesheet: Main.css Main.mxml joshphotography_edited-1/src line 3 Flex Problem
Your help is much appreciated it. I like the program, but if I continue to have problems... i'm going to have to abandon it.
I may have found a fix for this, although I'm not sure if this would be a 'best practice'. I kept running into the same problem, which was keeping me from Running the Project, or publishing to a SWF. What I did, after hours of trying stuff and trolling the net looking for answers, was publish the document as a .swf as soon as I imported the document from Illustrator, and stored the files in the same folder as my .fxp. It automatically created all of the source files and all of that. I was then able to create components and such and they ran in the browser just fine. I hope this helps.
P.S. Thanks to Adam Cath, I was able to figure this out by looking at your file structure in my course files from your Catalyst 101 class at MAX.