Add to cart graphics shows for a split second then disappears. How to solve it?

[filing]

Hi,

I'm using Joomla 2.5.11 and Virtuemart 2.0.20b (Both joomla and Virtuemart states I have the latest versions). I have made no core modifications in Joomla nor in Virtuemart.

The add to cart button shows up for a split second (in product view) and then disappears when the web page is fully loaded.
What remains is just static text "Add to cart" (which functions fine to add goods to cart.), but no actual graphical button to be seen.
All other button graphics (and other graphics) loads fine.

If I stop the web page loading at just the right moment the graphics remains (although the rest of the page is not fully loaded)
Like so:


When the page fully loads it looks like this:


Is this a known issue or have I run into something odd? 

Any suggested solutions?
If you need more info I'd be happy to provide it.

Thank you.

[AH]

Check what is happening to the CSS for the button using firebug.

Then you can see what css file is being used - it could be an override to the standard CSS file of VM

[filing]

Naturally after posting this, I found that the template I was using was overriding the button to a non-existent image URL.
It was an easy fix once I understood what was going on.

[AH]