It's not an issue with any browser, the site is just plain down. It could mean the parent group has changed hands or shut down, or they are performing a poorly-planned makeover of the site. They don't update their twitter or have a facebook page though, so there's no way to know.
It kind of worries me, 1Branson was a good site to occasionally plug SDCFans. I'm pretty sure most of our members migrated from there. It was a fairly well run forum too, the only other place to talk about Branson (other than here), is topix, which is full of racists and crazy people and isn't moderated.