Adsense media ads don't work?

[Jasonsc]

I have a small adsense site and I have been getting reports that the media ads cannot be seen in either chrome or mozilla, but work fine in IE.

I find this very strange.

Anyone have any experience of this? I've switch my media ads to text ads but it makes the site look very ad spammy without the media ones.

Advice? Anyone else have any experience of this?

Thanks,
Jason