Thanks for the reply! I don't seem to get any response when I try the Alt+F keys. I've now tried pretty much every option, and tried both 32 & 64-bit ISO's.
It always seems to fail when it comes to creating/formatting the ext4 filesystem - sometimes on md0, sometimes on sda3 (I guess this is defined by my choice of raid/no raid).
This is the first time I've tried installing on VMWare 6 - previous installs were on VMware 3 & 4. Will try to see if I can install an older VMware on a machine to test.
ETA - I have tried disk sizes of 40 & 60GB