Front end user only : when clicking on the submit button nothing appens

Hi

It seems that the plugin doesn't function properly : when clicking on the submit button nothing appens (no error message if the fields aren't fullfilled correctly or no confirmation message appear).
By the way the messages are taken into account (recorded and mail sent)
As the user doesn't see anything I receive 20 mail for one form. And maybe I'm missing customer that doesn't see error message and think it is send...

Here is an error (extract from chrome tool) :
Uncaught SyntaxError: Unexpected number /demande-de-renseignement/:354
Here is the code at line 354 (only the beginning) : <script type='text/javascript'>function gformInitSpinner_11(){jQuery(....
And the error in Firefox tool :
illegal character
...'disabled');if(form_content.length > 0 && !is_redirect){jQuery('#gform_wrap... /deman...nement/ (line 348, col 1072)

Here is the page you can find the form : http://www.littledancer.fr/demande-de-renseignement/

I also have a problem with the Chosen plugin : the close/delete button doesn't appear after each choice made in the multiple select field (the search icon in standard select as well but I don't care...)

This plugin worked perfectly previously, maybe it is the recent update...
It is a problem wit jQuery probably but I'm a noob and can't help myself...
FYI, I'm using striking theme.

Thanks for your help
JG

Thanks for your answer.
The plugin is working properly with twentyten theme and all plugin activated.
The plugin doesn't work properly with striking theme and only GF plugin activate
It must be a theme conflict...
Do you have an idea.
I'm pretty sure the problem appeared with the last recent update of GF, the plugin was perfectly working with striking theme during august.

EDIT:
After a little search on the forum my problem seems close to the problem exposed here :
http://www.gravityhelp.com/forums/topic/167-not-working
+ the problem with chosen plugin...

Thanks