sometimes all pages of my show white
 

sometimes all pages of my show white screen whitout any terransfer of data

whats problem ?

No idea, you dont provide no info as to what may be causing your issue, hacks installed etc, a link to the site would actually help as well

my forum link is http://forum.doctormob.com

please give other idea about this issue

As i cant get it to load a blank white page and you say it only happens sometimes, this is something your host will have to look into and find out why its failing.

Is the host running php as a cgi?

Here is a page from the manual about troubleshooting blank or 'white' pages: http://www.vbulletin.com/docs/html/blank_pages

check this way you say but all of my configuration is true

this white screen happen about 3times in one day

Have you checked your error_logs to see if something is in there?

It would help if you responded to the question about how the host is running php and if its as a CGI?

Random white pages like you say your having, could be a cgi issue.

How about you post a link to a info.php file so we can see how the server is setup?