The cause of your issue is multifold.
First: Zen Cart does not specify the absolute path names to images by default - instead it uses the "base href" meta tag to tell browsers to prepend this URL to relative path names. Nothing wrong with this in and of itself. Second: FaceBook's Open Graph API does not read the "base href" meta tag when scraping your website to find an image. Not many websites use the "base href" meta tag... so understandable.
Huh? Why is this an issue?
Why can they find the image with URL rewriting disabled but not when URL rewriting is enabled? As FaceBook does not currently use the "base href" meta tag it assumes the path is relative to the current page - not the website. Zen Cart Dynamic URLs are always on the website root - so everything works. Your rewritten URL contains a directory and is not on the website root - so it tries to access "http://www.disotech.it/console_giochi/bmz_cache/a/a1e9901b302de7165e1bd14bbca5b5ab.image.190x190.jpg" because you are in the directory "/console_giochi/". As there is no image at the location (404) FaceBook does not include an image.
How to Fix
1) Use Zen Cart Dynamic URLs or do not use directories in your rewritten URLs. Relatively easy, but not as pretty.
2) Change your templates to not depend on the "base href" meta tag. Specify all resources (images, css, javascript, etc) as absolute paths. This option works well and I have a couple client's whose templates do not use the "base href" meta tag. This can be complicated (find someone who knows templates and XHTML) and may involve changes to Image Handler (a plugin you are using).
3) Add the appropriate Open Graph tags to your individual pages. See http://goo.gl/xFI0u for more details. This is currently FaceBook's preferred method for you to communicate how a URL is shared on FaceBook. I do not currently know of any plugins to automate / aid in this process.
4) Request FaceBook update their API to utilize the "base href" meta tag when parsing a URL to determine the image / video to display. Wait for them to implement the change... No guarantee they ever will.