You can try adding extra Memory and threads when VRF fails due to low memory. But if it fails because of the following error, you will need to follow the below listed steps.
Tue May 1 16:29:29 2012: restarting VisualRF Engine...
HTTP server failed on port 6654
Tue May 1 16:37:53 2012: restarting VisualRF Engine...
VRF has its own WEB Server which runs on port 6654.
If you see the above error, it means that port 6654 is being utilized by some other service.
# netstat – anp | grep 6654
This will give a clear idea about the process using this port.
Steps to fix it:
1: Disable VRF from Webpage
2: Restart Apache, this will restart all the services (7.3 onwards) else RD will help.
3: Enable VRF from the Web page.