I found out that it has nothing to do with my lion installation because creating a new vm in the same vmware installation on the same os x lion helped. So I tried to investigate where the problem is but found nothing special in comparison to my new vm.
Here is my comparison table:
| step | problem vm | working vm |
|---|---|---|
| being in setup via F2 | 100% cpu | 0% cpu |
| being in grub - don't boot | 100% cpu | 100% cpu - why?? |
| after boot | 100% cpu | 0% cpu |
so I played a bit with my problem vm and changed the network interface. Switched off and found 0% cpu at phoenix setup. Changed from automatic to ethernet and switched on again: 0% cpu. So did I found something: no. Starting my second problem vm with automatic network discovery worked also.
Strange but it works again...