While browsing I noticed the extra space on the side. :)

Are you referring to not having the ads displayed? If so, you most likely have got some sort of ad blocking software installed locally, or the specific ad (if it only occasionally happens) is blocked.

I don't have any form of AD Blocker isntalled on my PC currently. I'm seeing the ads on the now though.

I have noticed this also sometimes even on multiple computers.

Fair play; I haven't ever noticed this, it looked exactly like an ad has been blocked by the browser/ad-blocking software. :)

I have noticed this occasionally too. I think it's possible that it is the result of a few spare impressions not being allocated ads on the site.

Although I'm not sure if these are automatically filled if some become available. :)

All ads dead here, takes 1-2 minutes for it to time out and to load anything.