Comment 3 for bug 153596

[Bug 127643] reffered to when a webpage was visited containing those annoying "rollover" flash advertisements, the space that would be taken by the rollover is blanked out in white, covering up the webpage content (text / images) even though the advert was not hovered over.

The issue appears to be resolved in Gutsy Gibbon / Firefox 2.0.0.8. I will update the thread should it occur again, but from visiting the websites that initally displayed the behaviour, rollover adverts do not block the main page content until they are hovered over, and no longer hovering over they return to their regular banner ad size.

Thank you all for your help.