Sorting problem in particular category

[EIF]

Within some particular categories I have a sorting problem, where other categories the sorting is correct.
I set the default sorting options on Product Price and Ascending. But the sorting of products in that category isn'r responding to it. The sorting is just mixed.
When I manually set the sorting to Product Name and Ascending, it does sort on the name, but Descending instead of Ascending.
Changing back to sorting on Product Price doesn't affect. The sorting is still mixed.

Does someone knows what the problem is. An example where the sorting is wrong is: http://www.waterpijp-bong.nl/bongs/glas

Versions I use are:

Virtuemart: 2.0.24
Joomla: 2.5.14
PHP: 5.3.27

[EIF]

When I look now, it is default sorting on product price. When I set it to sort on Productname, it also does work. But setting it back on product price, it doesn't work anymore. After that, setting it to name doesn't work also anymore.

Does anyone have an idea?

[jenkinhill]

All I can think of is to check settings in Config/Product Order Settings  - there is no option to sort selected categories differently.

[EIF]

Those settings are correct. I set them again to be sure.
The strange thing is that now the default the sorting is correct, but when setting it to something else,  as a website visitor, the sorting is mixed up. Somehow the sort option don't work anymore. Really strange....