I'm not sure if this question belongs here, or over at serverfault, but I'll start here:
I have several sites hosted on one Hostgator server in their Provo UT datacenter. As an example of my problem, if I visit www.hastogo.com and click to browse through several pages, occasionally and randomly an image or two will fail to display.
I installed FireBug and activated the Net tab.
With it running, I did the above until I found the "broken" images. When I did, I checked them in firebug and it showed they had returned the "200 OK" status. When I mouse over the listing for that image in the firebug panel, the image displays. If I refresh the page or right-click and choose "Reload Image" they are always displayed.
Another user in the office has a Samsung tablet that this happens to even more often than with the PCs in the office. I tried it also on my Ubuntu laptop (12.04 using xfce desktop and Firefox Browser) and got the same result except I did not have firebug running to check status.
Should I be focusing my diagnostic on the server/datacenter, or on our local network? I thought I might have seen a similar issue on other websites, but I was not able to re-create the error except on sites that share our server.