makinist99 on "[Plugin: WP Mail SMTP] i cannot open settings page"

Hello
I can use this plugin several sites. it is working on all sites. But I have a problem with one of them.
I can not enter the plugin settings page.
if i select email plugin setting, a blank white page is opened (on right side admin panel, on left side admin menu is still seems

http://wordpress.org/extend/plugins/wp-mail-smtp/