vagrant up fails when it gets to the ssh part:

myterminal$ vagrant up
[default] VM already created. Booting if its not already running...
[default] Running any VM customizations...
[default] Clearing any previously set forwarded ports...
[default] Forwarding ports...
[default] -- ssh: 22 => 2222 (adapter 1)
[default] -- db2: 30003 => 30003 (adapter 1)
[default] Cleaning previously set shared folders...
[default] Creating shared folders metadata...
[default] Booting VM...
[default] Waiting for VM to boot. This can take a few minutes.
[default] Failed to connect to VM!
Failed to connect to VM via SSH. Please verify the VM successfully booted
by looking at the VirtualBox GUI.

Then when I subsequently try and connect using vagrant ssh or vagrant reload or similar, I get this:

myterminal$ vagrant reload
[default] Attempting graceful shutdown of linux...
SSH connection was refused! This usually happens if the VM failed to
boot properly. Some steps to try to fix this: First, try reloading your
VM with `vagrant reload`, since a simple restart sometimes fixes things.
If that doesn't work, destroy your VM and recreate it with a `vagrant destroy`
followed by a `vagrant up`. If that doesn't work, contact a Vagrant
maintainer (support channels listed on the website) for more assistance.

Please help! I'm really stumped.

Kind regards,

Luke