You should probably ensure that C:\Users\Christopher\My Documents\Blockland\ is writable!
Navigate to C:\Users\Christopher\My Documents\ and right-click on the blockland directory, then click "properties." Navigate to the Security tab, click "edit", and you'll get a window that looks like this:
Click that "Users" group if it's not already selected, and check the "Allow" checkbox next to "Full control." Click Apply, then OK. Try the Launcher again and let us know what happens.
