Unable to create/edit product

[coxi]

Hi,
I developped a VM 2.0.24 + J2.5.16 website. Last product has been added at the beginning of 2013 December.
In the early days of january, I had to modify some of products...
Unfortunatly, I am unable now to modify any field of the product. I can change the value on the screen (IE, Chrome or mozilla are the same) but "save" button doesn't work. I can't escape. I stay into the product page.

In normal situation, the page is made of three child-pages. But, for me, only one page. all 3 are on the same. one under each other...

I can't create/add product. Just modify it into database with adminmyphp.

I upgrade Joomla to 2.5.17 and VM to 2.0.26d. Nothing append.

Any idea ?
Regards