If Hero Zzyzzx has failed to see this on so many browsers but Superlman has seen it on more than one, I'd suspect something outside the browser but somewhat specific to Superlman. My first guess is a web proxy.

Some ISPs set up transparent web proxies (usually for caching) that don't require the browser to know that a proxy is being used. So Superlman's web traffic might be going through a proxy w/o Superlman knowing this and no software is bug free, including web proxies.

I had an ISP whose proxy would cache incomplete pages if I hit my browser's "Stop" button during the first load of the page (making it very hard to get the complete page later). Anyway, that is something that might be worth checking into.