Hi
You can try if you feel confident enough in Ubuntu configuration.
First you need to get the destination VM not getting deleted. Open for converter-worker.xml file (found in %ALLUSERSPROFILE%\VMware\VMware vCenter Converter Standalone\) and look for powerOffHelperVm. Set it to 'false' and restart worker service (VMware vCenter Converter Standalone Worker).
Once you have the target VM, attach to it and boot from a live CD, preferably the Ubuntu installation CD.
Study the link asajm posted is , here are two more about manual reconfiguration:
https://communities.vmware.com/message/2224694#2224694
https://communities.vmware.com/message/2844710#2844710
HTH,
Plamen