Saturday 17 January 2009 3:04:25 am

The best place to start is to look in your apache logs to see if you are getting a specific error back from the server.
Depending upon your setup you will find them in either your virtual host log folder e.g. /home/domainname/logs/
or
/var/log/httpd/
the error_log is the one to look at.
user the command:
tail error_log
as this will show the last 10 lines of the log file and it would be best to cause the blank page to appear just before looking at the log file so you know you are looking at the right error.

Blank pages are usually caused by a PHP configuration error.
Once you have the error then a google or search in the forum will probably highlight the answer. Otherwise copy and paste the error here.