you'll have to excuse me if what i say is completely useless, i've never used norton:
most virus protection softwares have an option to ignore threats, so you can probably just ignore blockland as a threat.
norton has a hard time differentiating between what's really a threat and what's not. blockland is by no means a threat, so if you can't block it you could probably just turn norton off while playing blockland.
or you can take it up with their technical support
