Well this was one that took me ages to fix..
But annoyingly I think I was being told about the problem in many other virtuemart posts, but im not sure.
I “thought” I had tried all the permissions fixes going, but still couldnt get it to work, but anyway here’s what I needed to do..
The problem that was occuring was virtuemart was failing to display the image thumbnails under the category section. The product image and thumbnail were fine, but the one on the category page wasn’t. Looking at the link it was calling the show_image_in_imgtag.php script but for some reason, if I called it manually to debug, it was giving me an internal server error.
Unfortunatly to make things harder because it was running on a cpanel install I didnt have access to all the files I would have liked to.
Anyway, the bottom line – the fix.
in your webroot directory where you have joomla or mambo installed there will be a components directory, I needed to chmod this 755. Once this was done, the images just kicked in.
Hope this saves someone some time!