Maximum Drawing Space

There’s probably a post on this already, I would have searched, but I don’t really know what I should be searching for.

I’m making a sort of game if you like, with a scrolling background. (while I’m at it, check out http://www.trevorvanmeter.com/flyguy it’s exactly what I want to make) Don’t worry, I’m not asking about how to scroll the background or anything like that. I’ve got a slightly more obscure problem though, I’ve not really heard of it. My document size is something like 500 x 400 and the scrolling background I’ve got at the moment is about 1500 x 400. This is as big as I can draw it, and obviously it doesn’t give much room for exploration, as it only takes about 10 seconds to see the whole thing. The problem is, 1500 is about as wide as I can draw it. For some reason, flash won’t let you draw any wider (if you zoom right out there’s like a black line boundary that you can’t draw outside of) Now, the question, is there any way to increase this boundary? Or is there another way I can draw a bigger background? I don’t really want to use more than one tile, I can’t be arsed with the actionscripting. Any suggestions?