Unable to install.packages(): system call failed: Cannot allocate memory; installation of package had non-zero exit status

I figured out. I was all about the swap value.
There are several web pages that advice to decrease the default swap use in order to speed up Ubuntu. What I did to fix the problem.

In the terminal...

#Know the swap value    
cat /proc/sys/vm/swappiness
10
# Access the swap configuration
gksudo leafpad /etc/sysctl.conf

# Increase the swap usage to 30 (default is 60)
vm.swappiness=30

Then, I rebooted. And installed the packages happily without any problems.