Keef,
Using IE6 I get a variety of errors - 404, red cross, page cannot be found - plus some "ads", including all those mentioned in the thread, of which the most "virulent" is the CACHEBUSTER mentioned above.
I suspect that each time the page is hit, a random ad is inserted. Some of these no longer connect to the source, hence the errors. You can cycle through by using shift + refresh.
I will mention it to the powers that be - this doesn't fit well with the "spam-free" claim in the bullets above the ad!
SD