Increase memory_limit 128M
Many issues that you may run into such as; white screen, demo content fails when importing, empty page and other similar issues are all related to low PHP configuration limits. You can check it by installing a simple plugin found here.
The solution is to increase the PHP limits.
You can do this on your own .
Find the php.ini file in your Server config files.
For WAMP, its in apache2/bin/apache2.2.22/bin/php.ini
Go to the line “max_execution_time=30” .
Change it to 360 or any other large value.
Or contact your web host and ask them to increase those limits to a minimum as follows