indesign weird white thin line in pdfs?


I'm find that everytime O produce a pdf from indesign and I have a shape with DROP SHADOW filter applied and it sits on a photo, it give a while thin line around the boundary of the shape, take this example, look at the yellow oval, see the square thin white line? :

Anyone got any ideas?

thanks in advance.
Ignore it.

It's annoying onscreen, but it won't print that way, nor will it rasterize in Photoshop with the lines.

I've been dealing with that for years now and so far it has only manifested itself on screen.
I get the same thing, (fwiw I will be moving this to design) on my letter heads, resume etc etc, only Preview on mac shows it, Acrobat etc shows it correctly.
I'm afraid that Acrobat shows it for me. ANyway, I've realised that if you set indesign to save pdf as version 5 and above, all is fine! phew!
The line is the way the transparency is rasterized in versions of PDF that do not support transparency.

In other words, the image is broken up into parts so that the transparency can be rendered into a bitmap of said image. The thin white line is the division between the rasterized transparency and the rest of the artwork.

That is also why you don't see this in ver. 5+ PDFs: said version supports transparency.

However, open one of these transparency supported pdfs in an older version of a PDF reader, and you'll get ugly results.

Try it.