I just made an example, but realised there's a small change in the file format in 0.98.4, and it won't load in 0.98.3 if I upload it... beh. Still, unbounded scrolling with Start of Layout - set Zoom to 200, 200 was working just fine.
Here's the .cap Davioware mentioned, we were doing it exactly as you described:
http://willhostforfood.com/files3/9756073/wonky.cap
And here's a screenshot of what it's doing in case it actually is working fine for you:
<img src="http://i42.tinypic.com/330qn90.png">
What's happening is:
1. The black bars
2. Tiled BG objects disappearing when they get near the edge of the screen
3. The pink sprite with 8Dir on it doesn't show at all