Well this worked for me and I guess this thread will serve as a self reference also. Logged in ISPconfig, under "System", choose "Server Config" from the left menu and then choose the web server for which you want to avoid the open_basedir directive. Under tab "Web" change the "Security Level" option from high to medium. Enjoy
The open_basedir restriction is put on accounts to prevent users in a shared environment from accessing each others files or executing malicious scripts.This error message is common when a user tries to access a site via IP address prior to a DNS propagating. In other words, you have just set up a hosting account and are working on your site.Once the DNS propagates, you can access your site via your domain name.