Switch to using opendns.com DNS servers instead of Tiscali provided ones. I think this will do it.
208.67.222.222
208.67.220.220
Tiscali DNS servers are (I assume) currently doing your lookups, when a lookup fails they can direct you to whatever they want as they're in control. Opendns do actually do something similar in some instances, but you might like it better than Tiscali, give it a go.