I've been working on speeding up my pages and have now added ob_start("ob_gzhandler"); to the top of all of them. This works great, except that as soon as super cache is turned on the pages no longer display, even in super cache is set to half-on mode. I originally assumed this was due to having compression turned on in wp super cache, but it still doesn't work when this is turned off. Is there a known conflict and any way around it?
EDIT: Actually, this is rather bizarre. I have two sites that are pretty much identical - the themes are based off of each other, with only a small change made to the colour-scheme. On one I get no page displayed as described above, on the other it works fine. They're using the same host etc etc - identical in every way I can think of!