Any of my users cannot download the photos

[Anda]

Hi there!

Some visitors are complaining to me that they can't download the photos in the gallery. After right-clicking the picture would disappear. I´m sorry for bothering you. I know this question was here before.
I haven´t the hotlink protection enabled. I didn´t create the .htaccess file for it so I really don´t know what I have to edit or change.

Help PLEASE. Thank you  

Anda
http://www.ralph-fiennes.net/gallery/

[kegobeer]

What pictures are you talking about?  I was able to view your pictures and save any of them I wanted to.  Nothing disappeared.

[Anda]

I know , I haven´t the problem with downloading too.

But I got the emails and the messages in the guestbook from only very few visitors. They are talking about various sized (thumbnails, enlarged) pictures.
After right-clicking the picture would diminish into little grey cube or something as this 

I just don´t know what I should advise them.

Thank you for quick answer.

[Tranz]

I got the same results as kegobeer. I could view and save.

It's hard to figure out the problem when we can't see it.

[kegobeer]

I'll guess it's on the client end, not the server end.  Software firewall, javascript settings, odd PC setup, etc, could all contribute.

[Anda]

I think it's on the client end too.

"Software firewall, javascript settings, odd PC setup, etc"
Thank you for your suggestions!