Hi,
To avoid the problem, you should set specific ordering values for your products.
Because you display products from different categories in a single page, the value "ordering" is not a consistency value.
Using a more "fixed" value like the product name assure that the sorting make by the database will be always the same.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.