Bulk order quantity defaulting back to 1 on checkout

[Guest]

I am using MS1, and with a new shop (everything else running fine, this was last minute testing), if I try to order a bulk quantity of the product higher than 1 (9 or 10 for example), upon checkout the quantity goes back to 1.

There is only one product on the site, and no mods other than 'CanadaPost' and an 'Update Currency' cron job.

Any help greatly appreciated, as the client is relying on bulk orders for this product and we'd planned on opening shop July 6th.

:cry:

Thanks,

Violet