I'd like advise please, so I can share my data!
This may not help you much.
With 090b13, XPSP2 and java 1.6.0_02-b06, I have no problem exporting as PNG or JPG, although SVG is a problem ("null incompatible with Global antialiasing enable key") (which I though was recorded but now I can't find it!)
Likewise I can export for both Flash and Java.
Now I'll pick up on something you weren't explicit about. When you send the export to others you have to send a .html file, and a folder whose name ends in .html_files, and that folder's contents. (The contents differ for flash & java.)
You're probably doing that since you're referring to browser errors, but thought I'd clarify.
I also have problems with exporting in any file format.
The following do not work under fc6:
The only thing that works for me is to print to file (which is also broken but fixable) and use ghostscript to convert to the output format that I need.
Try setting the zoom on your map to "Zoom to fit to page." This works for me with 0.9.0 beta 14.
It will probably make an illegible image if you have a sufficiently large map. You might workaround by unfolding branches, exporting images and stitching together the result. That counts as a nasty work-around in my opinion.