After a crash during an update (which I managed to recover from), the default file manager Nautilus no longer works, and crashes so hard it crashes VirtualBox too.
I tried by deleting it then reinstalling it, but didn’t change this behavior. Also there’s a non-zero possibility that the original crash was caused by Nautilus itself.
Perhaps the OP means that when they open nautilus in the host it crashes virtualbox? It could be ram usage climbing up and the OOM killer taking out virtualbox?