I have a strange situation that happens fairly often in my builds. I have a common swc file that is shared between several different swfs. Several times a week, all my swfs break after building through the command line due to these newly built swfs not explicitly requesting to download the dependant swc file. I figured this out by using Charles, a web debugging proxy. At first I thought this was a caching issue, however it happens across browsers, in different computers with different OS's. Even clearing the cache on the browser does not fix it. The swf file progress bar just sits there at 100% and never completes loading.
I am using Flex SDK 3.3 on a Windows 2000 server machine to build.