I'm not sure where this problem can be emanating from exactly, however I seem to have run into an interesting issue, where the Ad Injection widgets I use for my separate sub-sites seem to be crossing over.
On one subsite, i use Ad Injection to display a random group of affiliate links through a certain network while on my other subsite (there are many more but these are the two with ads at the moment) uses a google Adsense block. What started happening was that this Google Adsense block started displaying on the first sub site all of a sudden. I went into the widget menu and re-saved settings to fix this, however it seemed to come back later and I had to turn off Ad Injection on the site to keep it from happening again.
Any ideas what may be behind this?