Sometimes in the product-detail will hide the category-menu placed on the sidebar, The Module shows on the bottom instead of in the sidebar. you can visit my webseite stone-spirit.ch, click on a product and sometimes you can see the failure. I use Mac Safari and Firefox.
Update: now it works!
I change in the Virtuemart Backend under Style-Tempate the Product-Layout Option from no setting to default-original. But anyway, maybe thats only a workarround. I hope you can fix the Bug with the default Setting.
Please look at my other Topics, i need urgently your support!