Black background behind icons for categories?

I am using png images with a transparent background as the image icons for different categories. The pictures, however, are displaying in the browser with a black background where it should be transparent. I have examined the CSS with firebug, but can't seem to find a reason these backgrounds are being displayed. Any input from anyone?

Can you send me the link to that page so that I can check it for you ?

Regards,

Tuan

I am also having this same problem. Did you find a fix for it?

@darkly : Could you please send me the link to the page so that I can have a look at it to see what's causing the problem ?

Regards,

Tuan

Sure, I just emailed you.

any update on this?

@darkly : It seems the black background was added when the thumbnail was generated. However, I cannot re-procedure the issue on my local computer.

Could you please submit a support ticket sending me administrator and FTP account of your site so that I can check it directly on your site ?

Regards,

Tuan