Hello, I had the same problem with Redhat EL4 (ESX to workstation, "Error Loading Operating System" after successful conversion)
The problem was a conversion option. First time, the volume was rezised (shrunken) and splitted into 2GB-files. That doesn't work with Linux.
On second attempt by choosing Option "Maintain size" and no splitting, the converted VM booted without problems.
I think the problem was solved by the "Maintain size" option.
Cheers,
Simone