Running third party vmware images

Trying to reconfigure mail once again (a rant for another time) and trying out a couple of VMware Virtual Appliances. But every appliance I tried on my server would just appear to hang. Black screen, no bios, no nothing. Finally found a post on the VMware forums talking about permissions, so I compared my working images to the non-working ones and the problem was simply that the .vmx file needed to have execute permissions.