VMWare OVA file
Have you tried unzipping the .OVA into an .OVF?
edit - found THIS, quite useful.
Question is >6 month old, but as I had the same problem; here is my solution:
Convert the .ova file to an .vmx with the VMWare ovftool: http://www.vmware.com/resources/techresources/1013
The converted .vmx file can be executed with VMWare Player.