problem with one item on website not adding to basket

[3000rpm]

hi there

i have a strange problem where one item when you go to order it it doesnt add to basket and comes up with error

"Quantity: The quantity must be a whole number greater than or equal to 1."

http://www.3000rpm.com/acatalog/One_..._25_Pack_.html

the settings are the same from what i can see from within actinic and i have done a full refresh also.

can anyone help please

[RuralWeb]

It could be that in "View | Business Settings | Ordering", under "Miscellaneous", you have ticked "Order Quantity Always One".

[TraceyHand]

is it happening on ALL the duplicates for that product?
Does the original work?
Where is the original located in your catalog/store?