You shouldn't attach that because it contains too much vBulletin code.

But, double check everything because it's working fine for others. It could also be a conflict with some other mod you have installed.

When this is enabled some thumbnail images become broken? When disbaled, they all work just fine. Any idea?

No idea... Do you have any other attachment/thumbnail related hacks running that may conflict?

Thank you, Works like a charm!

This mod is great - thank you for sharing!

One issue (and I think it's me being thick or just the way vB works) - I display images in line to registered users (no pesky thumbnails). If I want to show thumbs to unregistered users, I need to turn on thumbnails (and build them), but there seems to be no way to now let registered users to view in line.

So, can I show thumbs to unregistered users but still show full images inline to registered users?

Not without some additional hacking/mods....

Thanks - was just checking I understood it correctly.

One more thing - when the watermark is displayed (I'm using a transparent png) the overall quality of the displayed jpg goes down quite significantly. Is there any way around this?

I tested your attachment, works without problems.

Check if you really change your Attachment Storage Type into Filesystem

And the path to watermark image is correct in AdminCP -> vBulletin Options -> Attachment Watermarks

How about pictures putted via [ IMG ][ /IMG ] tags? Is there any way to put a watermark on them,too?

No, this works for attached images only. If the images are on other servers you don't have any control over them, so you can't.

( Plus, they aren't on your server anyway, so you don't really have the right to watermark them. :D )