Error page when modifying a view

Hello,

i have a problem that seems to come from nowhere when i try to add or modify an element (label, inputfield...) in a view :

the view window displays an error html page saying that the program can't display the web page.

If i close the view and open it again, the modifications i've done appear but then again, if i try to change anything, the error page is displayed.

Does anybody have a clue of howw to solve this ?

Thanks