Some additional discoveries.

the vmware.log file in the vm's folder shows an entry saying "/usr/lib/vmware/settings": No such file or directory."

And this directory is really missing. I seems to be it has to be removed by "something" because it was working before.

I'm wondering whether it would help to uninstall vmplayer but leave the virtual-machine intact.

I also installed a totally new vm (Linux) from the source ISO and this vm is also not launching. It shows the same behavior as the 'moved' vm's before.

I'm quite puzzled.

Cheers