I'd have to go back through my notes but I thought there was a reason I was on 4.1. Wasn't it UBB that didn't support the new version, 5.0? Or is that limitation gone with this new release of software? If so I'll gladly update to 5.0 and see if that helps ...
The old version had *all* sorts of problems - content islands got stuck daily, the forums ran really slowly, etc. So that was just sick in general. The new version is generating content islands fine, it runs quickly, so we're just down to it crashing occasionally
Since crashing is such a generic "something has failed" thing, I'm not sure we can really compare them against each other yet.