Sorry about this error.
I am afraid you need to reinstall your WhatsApp application. Something went wrong here. And because it is a third-party application, we do not have insights on what is wrong.
So your course of actions are:
1. Try reinstall WhatsApp;
2. If #1 does not work, try to go to <user id>/.Virtualbox/HardDisks. Rename youwave_vm01.vdi. Copy youwave_vm01_golden.vdi to youwave_vm01.vdi. Then restart YouWave.
Either way, you restart WhatsApp from the beginning.