Oh yeah, one other thing... it tells me that the error is on line 30. Even if I remove virtually all of the MXML, so that the file is only 10 lines long, it still tells me I have an error on line 30. Whatever I do, the error is always on line 30.
opps, disregard my message below, I just noticed that the error reads that it is coming from your main app file.
How many projects do you have open? If you have several open, and one is marked as the default app to run(marked with blue circle), then the errors could possibly be from that other project. Just something to check . . .
Ah, thanks! That's it - well, almost. It wasn't another project, but Flash Builder had marked my other Window component as another Application to run within the same project. Once I went into the project settings and removed it as an application, everything ran fine without any errors.