If you look at the screengrab attached a 1px gap appears to the right of the divs in the scroller, drop down menu and also distorts the title of the "Enquire Now".
If I remove the flash banner everything is fine. Is there a Flash bug on Firefox that I have missed or any suggestions on what to try ?
There is a general flash bug on any browser on Macs which makes flash run pretty badly. It's much slower on Macs. Wouldn't surprise me if there were other bugs such as this.
Pretty much every Mac user I know has click2flash installed which blocks flash entirely...