Wrong URL for "sort by" and "show products per page"

[drolly]

Hi
I've this problem: on category page when change the sorting or the number of product per pages Virtuemart redirects me to the page of another category!
Go to my site on this page and try to change sorting:
http://shoutkey.com/sprain

You will be redirected to a wrong category.
Can I solve this?

[jenkinhill]

http://forum.virtuemart.net/index.php?topic=79799.0

[drolly]

Joomla! 2.5.24
VirtueMart 2.6.6
Live URL: http://shoutkey.com/hypertension

[jenkinhill]

First you should update:  http://virtuemart.net/news/latest-news/462-security-release-of-vm2-6-10-and-vm2-9-9b
and http://www.joomla.org/announcements/release-news/5563-joomla-2-5-25-released.html

Can't see the url as the address just resolves to an IP number.