If you want to add a filesystem to mount in /etc/fstab you need to use the octal ASCII value which is \040. In my case I have created a separate filesystem for VMware virtual machines:

/dev/mapper/vmwarefs      /var/lib/vmware/Virtual\040Machines     ext3     defaults     1 1

If you have any other special characters which are causing problems you can check with

man ascii

for the value you need to specify.