What?
I've never heard of those.
My oldest build is probably the "demo limit" in Bedroom, I remember I built it and then somehow it got in every copy of Blockland.
And no Badspot can't 'retrieve' the build.
It's probably a hard drive error, if you're on Vista you need to install Blockland to the C:\ drive, not Program Files, otherwise security crap will affect its ability to write saves in its own folder.