Problem solved!
For all that are getting the same error message:
I have a resolume arena server running v-control to do some projektor and air conditioning powering on and off. The arena server was triggered through the localhost network adapter (127.0.0.1 in v-control). After a recent update to arena 7, the network interface in arena changed from localhost to the internal realtek card. That was causing v-control to crash in show load. After i changed the network interface in arena back to localhost everything worked as it should.
Andreas